The value of super_block::s_blocksize_bits is the same as
fs_info::sectorsize_bits, but we don't need to do the extra dereferences
in many functions and storing the bits as u32 (in fs_info) generates
shorter assembly.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This effectively reverts 09745ff88d93 ("btrfs: dio iomap DSYNC
workaround") now that the iomap API has been updated to allow
iomap_dio_complete() not to be called under i_rwsem anymore.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If direct writes are called with O_DIRECT | O_DSYNC, it will result in a
deadlock because iomap_dio_rw() is called under i_rwsem which calls:
iomap_dio_complete()
generic_write_sync()
btrfs_sync_file()
btrfs_sync_file() requires i_rwsem, so call __iomap_dio_rw() with the
i_rwsem locked, and call iomap_dio_complete() after unlocking i_rwsem.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The inode dio_sem can be eliminated because all DIO synchronization is
now performed through inode->i_rwsem that provides the same guarantees.
This reduces btrfs_inode size by 40 bytes.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Direct writes within EOF are safe to be performed with inode shared lock
to improve parallelization with other direct writes or reads because EOF
is not changed and there is no race with truncate().
Direct reads are already performed under shared inode lock.
This patch is precursor to removing btrfs_inode->dio_sem.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Push inode locking and unlocking closer to where we perform the I/O. For
this we need to move the write checks inside the respective functions as
well.
pos is evaluated after generic_write_checks because O_APPEND can change
iocb->ki_pos.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_inode_lock/unlock() are wrappers around inode locks, separating
the type of lock and actual locking.
- 0 - default, exclusive lock
- BTRFS_ILOCK_SHARED - for shared locks, for possible parallel DIO
- BTRFS_ILOCK_TRY - for the RWF_NOWAIT sequence
The bits SHARED and TRY can be combined together.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_write_check() checks write parameters in one place before
beginning a write. This does away with inode_unlock() after every check.
In the later patches, it will help push inode_lock/unlock() in buffered
and direct write functions respectively.
generic_write_checks needs to be called before as it could truncate
iov_iter and its return used as count.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
fs_info::fs_state is a filesystem bit check as opposed to inode and can
be performed before we begin with write checks. This eliminates inode
lock/unlock in case the error bit is set.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
While we do this, correct the call to pagecache_isize_extended:
- pagecache_isize_extended needs to be called to the start of the write
as opposed to i_size
- we don't need to check range before the call, this is done in the
function
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The read and write DIO don't have anything in common except for the
call to iomap_dio_rw. Extract the write call into a new function to get
rid of conditional statements for direct write.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
Set the extent bits EXTENT_NORESERVE inside btrfs_dirty_pages() as
opposed to calling set_extent_bits again later.
Fold check for written length within the function.
Note: EXTENT_NORESERVE is set before unlocking extents.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
round_down looks prettier than the bit mask operations.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
write_bytes can change in btrfs_check_nocow_lock(). Calculate variables
such as num_pages and reserve_bytes once we are sure of the value of
write_bytes so there is no need to re-calculate.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a buffered write, through one of the write family syscalls, we
look for ranges which currently don't have allocated extents and set the
'delalloc new' bit on them, so that we can report a correct number of used
blocks to the stat(2) syscall until delalloc is flushed and ordered extents
complete.
However there are a few other places where we can do a buffered write
against a range that is mapped to a hole (no extent allocated) and where
we do not set the 'new delalloc' bit. Those places are:
- Doing a memory mapped write against a hole;
- Cloning an inline extent into a hole starting at file offset 0;
- Calling btrfs_cont_expand() when the i_size of the file is not aligned
to the sector size and is located in a hole. For example when cloning
to a destination offset beyond EOF.
So after such cases, until the corresponding delalloc range is flushed and
the respective ordered extents complete, we can report an incorrect number
of blocks used through the stat(2) syscall.
In some cases we can end up reporting 0 used blocks to stat(2), which is a
particular bad value to report as it may mislead tools to think a file is
completely sparse when its i_size is not zero, making them skip reading
any data, an undesired consequence for tools such as archivers and other
backup tools, as reported a long time ago in the following thread (and
other past threads):
https://lists.gnu.org/archive/html/bug-tar/2016-07/msg00001.html
Example reproducer:
$ cat reproducer.sh
#!/bin/bash
MNT=/mnt/sdi
DEV=/dev/sdi
mkfs.btrfs -f $DEV > /dev/null
# mkfs.xfs -f $DEV > /dev/null
# mkfs.ext4 -F $DEV > /dev/null
# mkfs.f2fs -f $DEV > /dev/null
mount $DEV $MNT
xfs_io -f -c "truncate 64K" \
-c "mmap -w 0 64K" \
-c "mwrite -S 0xab 0 64K" \
-c "munmap" \
$MNT/foo
blocks_used=$(stat -c %b $MNT/foo)
echo "blocks used: $blocks_used"
if [ $blocks_used -eq 0 ]; then
echo "ERROR: blocks used is 0"
fi
umount $DEV
$ ./reproducer.sh
blocks used: 0
ERROR: blocks used is 0
So move the logic that decides to set the 'delalloc bit' bit into the
function btrfs_set_extent_delalloc(), since that is what we use for all
those missing cases as well as for the cases that currently work well.
This change is also preparatory work for an upcoming patch that fixes
other problems related to tracking and reporting the number of bytes used
by an inode.
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Since we switched to the iomap infrastructure in b5ff9f1a96e8f ("btrfs:
switch to iomap for direct IO") we're calling generic_file_buffered_read()
directly and not via generic_file_read_iter() anymore.
If the read could read everything there is no need to bother calling
generic_file_buffered_read(), like it is handled in
generic_file_read_iter().
If we call generic_file_buffered_read() in this case we can hit a
situation where we do an invalid readahead and cause this UBSAN splat
in fstest generic/091:
run fstests generic/091 at 2020-10-21 10:52:32
================================================================================
UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
shift exponent 64 is too large for 64-bit type 'long unsigned int'
CPU: 0 PID: 656 Comm: fsx Not tainted 5.9.0-rc7+ #821
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4-rebuilt.opensuse.org 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:77
dump_stack+0x57/0x70 lib/dump_stack.c:118
ubsan_epilogue+0x5/0x40 lib/ubsan.c:148
__ubsan_handle_shift_out_of_bounds.cold+0x61/0xe9 lib/ubsan.c:395
__roundup_pow_of_two ./include/linux/log2.h:57
get_init_ra_size mm/readahead.c:318
ondemand_readahead.cold+0x16/0x2c mm/readahead.c:530
generic_file_buffered_read+0x3ac/0x840 mm/filemap.c:2199
call_read_iter ./include/linux/fs.h:1876
new_sync_read+0x102/0x180 fs/read_write.c:415
vfs_read+0x11c/0x1a0 fs/read_write.c:481
ksys_read+0x4f/0xc0 fs/read_write.c:615
do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9 arch/x86/entry/entry_64.S:118
RIP: 0033:0x7fe87fee992e
RSP: 002b:00007ffe01605278 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 000000000004f000 RCX: 00007fe87fee992e
RDX: 0000000000004000 RSI: 0000000001677000 RDI: 0000000000000003
RBP: 000000000004f000 R08: 0000000000004000 R09: 000000000004f000
R10: 0000000000053000 R11: 0000000000000246 R12: 0000000000004000
R13: 0000000000000000 R14: 000000000007a120 R15: 0000000000000000
================================================================================
BTRFS info (device nullb0): has skinny extents
BTRFS info (device nullb0): ZONED mode enabled, zone size 268435456 B
BTRFS info (device nullb0): enabling ssd optimizations
Fixes: f85781fb50 ("btrfs: switch to iomap for direct IO")
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit 8d875f95da ("btrfs: disable strict file flushes for
renames and truncates") eliminated the notion of ordered operations and
instead BTRFS_INODE_ORDERED_DATA_CLOSE only remained as a flag
indicating that a file's content should be synced to disk in case a
file is truncated and any writes happen to it concurrently. In fact
this intendend behavior was broken until it was fixed in
f6dc45c7a9 ("Btrfs: fix filemap_flush call in btrfs_file_release").
All things considered let's give the flag a more descriptive name. Also
slightly reword comments.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The passed in ordered_extent struct is always well-formed and contains
the inode making the explicit argument redundant.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
That parameter can easily be derived based on the "data_size" and "nr"
parameters exploit this fact to simply the function's signature. No
functional changes.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The value of this argument can be derived from the total_data as it's
simply the value of the data size + size of btrfs_items being touched.
Move the parameter calculation inside the function. This results in a
simpler interface and also a minor size reduction:
./scripts/bloat-o-meter ctree.original fs/btrfs/ctree.o
add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-34 (-34)
Function old new delta
btrfs_duplicate_item 260 259 -1
setup_items_for_insert 1200 1190 -10
btrfs_insert_empty_items 177 154 -23
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that we use the same mechanism to replace all the extents in a file
range with either a hole, an existing extent (when cloning) or a new
extent (when using fallocate), the name of btrfs_insert_clone_extent()
no longer reflects its genericity.
So rename it to btrfs_insert_replace_extent(), since what it does is
to either insert an existing extent or a new extent into a file range.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The function btrfs_punch_hole_range() is now used to replace all the file
extents in a given file range with an extent described in the given struct
btrfs_replace_extent_info argument. This extent can either be an existing
extent that is being cloned or it can be a new extent (namely a prealloc
extent). When that argument is NULL it only punches a hole (drops all the
existing extents) in the file range.
So rename the function to btrfs_replace_file_extents().
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that we can use btrfs_clone_extent_info to convey information for a
new prealloc extent as well, and not just for existing extents that are
being cloned, rename it to btrfs_replace_extent_info, which reflects the
fact that this is now more generic and it is used to replace all existing
extents in a file range with the extent described by the structure.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The value of item_size of struct btrfs_clone_extent_info is always set to
the size of a non-inline file extent item, and in fact the infrastructure
that uses this structure (btrfs_punch_hole_range()) does not work with
inline file extents at all (and it is not supposed to).
So just remove that field from the structure and use directly
sizeof(struct btrfs_file_extent_item) instead. Also assert that the
file extent type is not inline at btrfs_insert_clone_extent().
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing an fallocate(), specially a zero range operation, we assume
that reserving 3 units of metadata space is enough, that at most we touch
one leaf in subvolume/fs tree for removing existing file extent items and
inserting a new file extent item. This assumption is generally true for
most common use cases. However when we end up needing to remove file extent
items from multiple leaves, we can end up failing with -ENOSPC and abort
the current transaction, turning the filesystem to RO mode. When this
happens a stack trace like the following is dumped in dmesg/syslog:
[ 1500.620934] ------------[ cut here ]------------
[ 1500.620938] BTRFS: Transaction aborted (error -28)
[ 1500.620973] WARNING: CPU: 2 PID: 30807 at fs/btrfs/inode.c:9724 __btrfs_prealloc_file_range+0x512/0x570 [btrfs]
[ 1500.620974] Modules linked in: btrfs intel_rapl_msr intel_rapl_common kvm_intel (...)
[ 1500.621010] CPU: 2 PID: 30807 Comm: xfs_io Tainted: G W 5.9.0-rc3-btrfs-next-67 #1
[ 1500.621012] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 1500.621023] RIP: 0010:__btrfs_prealloc_file_range+0x512/0x570 [btrfs]
[ 1500.621026] Code: 8b 40 50 f0 48 (...)
[ 1500.621028] RSP: 0018:ffffb05fc8803ca0 EFLAGS: 00010286
[ 1500.621030] RAX: 0000000000000000 RBX: ffff9608af276488 RCX: 0000000000000000
[ 1500.621032] RDX: 0000000000000001 RSI: 0000000000000027 RDI: 00000000ffffffff
[ 1500.621033] RBP: ffffb05fc8803d90 R08: 0000000000000001 R09: 0000000000000001
[ 1500.621035] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000003200000
[ 1500.621037] R13: 00000000ffffffe4 R14: ffff9608af275fe8 R15: ffff9608af275f60
[ 1500.621039] FS: 00007fb5b2368ec0(0000) GS:ffff9608b6600000(0000) knlGS:0000000000000000
[ 1500.621041] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1500.621043] CR2: 00007fb5b2366fb8 CR3: 0000000202d38005 CR4: 00000000003706e0
[ 1500.621046] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1500.621047] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1500.621049] Call Trace:
[ 1500.621076] btrfs_prealloc_file_range+0x10/0x20 [btrfs]
[ 1500.621087] btrfs_fallocate+0xccd/0x1280 [btrfs]
[ 1500.621108] vfs_fallocate+0x14d/0x290
[ 1500.621112] ksys_fallocate+0x3a/0x70
[ 1500.621117] __x64_sys_fallocate+0x1a/0x20
[ 1500.621120] do_syscall_64+0x33/0x80
[ 1500.621123] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1500.621126] RIP: 0033:0x7fb5b248c477
[ 1500.621128] Code: 89 7c 24 08 (...)
[ 1500.621130] RSP: 002b:00007ffc7bee9060 EFLAGS: 00000293 ORIG_RAX: 000000000000011d
[ 1500.621132] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fb5b248c477
[ 1500.621134] RDX: 0000000000000000 RSI: 0000000000000010 RDI: 0000000000000003
[ 1500.621136] RBP: 0000557718faafd0 R08: 0000000000000000 R09: 0000000000000000
[ 1500.621137] R10: 0000000003200000 R11: 0000000000000293 R12: 0000000000000010
[ 1500.621139] R13: 0000557718faafb0 R14: 0000557718faa480 R15: 0000000000000003
[ 1500.621151] irq event stamp: 1026217
[ 1500.621154] hardirqs last enabled at (1026223): [<ffffffffba965570>] console_unlock+0x500/0x5c0
[ 1500.621156] hardirqs last disabled at (1026228): [<ffffffffba9654c7>] console_unlock+0x457/0x5c0
[ 1500.621159] softirqs last enabled at (1022486): [<ffffffffbb6003dc>] __do_softirq+0x3dc/0x606
[ 1500.621161] softirqs last disabled at (1022477): [<ffffffffbb4010b2>] asm_call_on_stack+0x12/0x20
[ 1500.621162] ---[ end trace 2955b08408d8b9d4 ]---
[ 1500.621167] BTRFS: error (device sdj) in __btrfs_prealloc_file_range:9724: errno=-28 No space left
When we use fallocate() internally, for reserving an extent for a space
cache, inode cache or relocation, we can't hit this problem since either
there aren't any file extent items to remove from the subvolume tree or
there is at most one.
When using plain fallocate() it's very unlikely, since that would require
having many file extent items representing holes for the target range and
crossing multiple leafs - we attempt to increase the range (merge) of such
file extent items when punching holes, so at most we end up with 2 file
extent items for holes at leaf boundaries.
However when using the zero range operation of fallocate() for a large
range (100+ MiB for example) that's fairly easy to trigger. The following
example reproducer triggers the issue:
$ cat reproducer.sh
#!/bin/bash
umount /dev/sdj &> /dev/null
mkfs.btrfs -f -n 16384 -O ^no-holes /dev/sdj > /dev/null
mount /dev/sdj /mnt/sdj
# Create a 100M file with many file extent items. Punch a hole every 8K
# just to speedup the file creation - we could do 4K sequential writes
# followed by fsync (or O_SYNC) as well, but that takes a lot of time.
file_size=$((100 * 1024 * 1024))
xfs_io -f -c "pwrite -S 0xab -b 10M 0 $file_size" /mnt/sdj/foobar
for ((i = 0; i < $file_size; i += 8192)); do
xfs_io -c "fpunch $i 4096" /mnt/sdj/foobar
done
# Force a transaction commit, so the zero range operation will be forced
# to COW all metadata extents it need to touch.
sync
xfs_io -c "fzero 0 $file_size" /mnt/sdj/foobar
umount /mnt/sdj
$ ./reproducer.sh
wrote 104857600/104857600 bytes at offset 0
100 MiB, 10 ops; 0.0669 sec (1.458 GiB/sec and 149.3117 ops/sec)
fallocate: No space left on device
$ dmesg
<shows the same stack trace pasted before>
To fix this use the existing infrastructure that hole punching and
extent cloning use for replacing a file range with another extent. This
deals with doing the removal of file extent items and inserting the new
one using an incremental approach, reserving more space when needed and
always ensuring we don't leave an implicit hole in the range in case
we need to do multiple iterations and a crash happens between iterations.
A test case for fstests will follow up soon.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It's counterintuitive to have a function named btrfs_inode_xxx which
takes a generic inode. Also move the function to btrfs_inode.h so that
it has access to the definition of struct btrfs_inode.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
iomap dio will run generic_write_sync() for us if the iocb is DSYNC.
This is problematic for us because of 2 reasons:
1. we hold the inode_lock() during this operation, and we take it in
generic_write_sync()
2. we hold a read lock on the dio_sem but take the write lock in fsync
Since we don't want to rip out this code right now, but reworking the
locking is a bit much to do at this point, work around this problem with
this masterpiece of a patch.
First, we clear DSYNC on the iocb so that the iomap stuff doesn't know
that it needs to handle the sync. We save this fact in
current->journal_info, because we need to see do special things once
we're in iomap_begin, and we have no way to pass private information
into iomap_dio_rw().
Next we specify a separate iomap_dio_ops for sync, which implements an
->end_io() callback that gets called when the dio completes. This is
important for AIO, because we really do need to run generic_write_sync()
if we complete asynchronously. However if we're still in the submitting
context when we enter ->end_io() we clear the flag so that the submitter
knows they're the ones that needs to run generic_write_sync().
This is meant to be temporary. We need to work out how to eliminate the
inode_lock() and the dio_sem in our fsync and use another mechanism to
protect these operations.
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We're using direct io implementation based on buffer heads. This patch
switches to the new iomap infrastructure.
Switch from __blockdev_direct_IO() to iomap_dio_rw(). Rename
btrfs_get_blocks_direct() to btrfs_dio_iomap_begin() and use it as
iomap_begin() for iomap direct I/O functions. This function allocates
and locks all the blocks required for the I/O. btrfs_submit_direct() is
used as the submit_io() hook for direct I/O ops.
Since we need direct I/O reads to go through iomap_dio_rw(), we change
file_operations.read_iter() to a btrfs_file_read_iter() which calls
btrfs_direct_IO() for direct reads and falls back to
generic_file_buffered_read() for incomplete reads and buffered reads.
We don't need address_space.direct_IO() anymore: set it to noop.
Similarly, we don't need flags used in __blockdev_direct_IO(). iomap is
capable of direct I/O reads from a hole, so we don't need to return
-ENOENT.
Btrfs direct I/O is now done under i_rwsem, shared in case of reads and
exclusive in case of writes. This guards against simultaneous truncates.
Use iomap->iomap_end() to check for failed or incomplete direct I/O:
- for writes, call __endio_write_update_ordered()
- for reads, unlock extents
btrfs_dio_data is now hooked in iomap->private and not
current->journal_info. It carries the reservation variable and the
amount of data submitted, so we can calculate the amount of data to call
__endio_write_update_ordered in case of an error.
This patch removes last use of struct buffer_head from btrfs.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently regardless of a full or a fast fsync we always wait for ordered
extents to complete, and then start logging the inode after that. However
for fast fsyncs we can just wait for the writeback to complete, we don't
need to wait for the ordered extents to complete since we use the list of
modified extents maps to figure out which extents we must log and we can
get their checksums directly from the ordered extents that are still in
flight, otherwise look them up from the checksums tree.
Until commit b5e6c3e170 ("btrfs: always wait on ordered extents at
fsync time"), for fast fsyncs, we used to start logging without even
waiting for the writeback to complete first, we would wait for it to
complete after logging, while holding a transaction open, which lead to
performance issues when using cgroups and probably for other cases too,
as wait for IO while holding a transaction handle should be avoided as
much as possible. After that, for fast fsyncs, we started to wait for
ordered extents to complete before starting to log, which adds some
latency to fsyncs and we even got at least one report about a performance
drop which bisected to that particular change:
https://lore.kernel.org/linux-btrfs/20181109215148.GF23260@techsingularity.net/
This change makes fast fsyncs only wait for writeback to finish before
starting to log the inode, instead of waiting for both the writeback to
finish and for the ordered extents to complete. This brings back part of
the logic we had that extracts checksums from in flight ordered extents,
which are not yet in the checksums tree, and making sure transaction
commits wait for the completion of ordered extents previously logged
(by far most of the time they have already completed by the time a
transaction commit starts, resulting in no wait at all), to avoid any
data loss if an ordered extent completes after the transaction used to
log an inode is committed, followed by a power failure.
When there are no other tasks accessing the checksums and the subvolume
btrees, the ordered extent completion is pretty fast, typically taking
100 to 200 microseconds only in my observations. However when there are
other tasks accessing these btrees, ordered extent completion can take a
lot more time due to lock contention on nodes and leaves of these btrees.
I've seen cases over 2 milliseconds, which starts to be significant. In
particular when we do have concurrent fsyncs against different files there
is a lot of contention on the checksums btree, since we have many tasks
writing the checksums into the btree and other tasks that already started
the logging phase are doing lookups for checksums in the btree.
This change also turns all ranged fsyncs into full ranged fsyncs, which
is something we already did when not using the NO_HOLES features or when
doing a full fsync. This is to guarantee we never miss checksums due to
writeback having been triggered only for a part of an extent, and we end
up logging the full extent but only checksums for the written range, which
results in missing checksums after log replay. Allowing ranged fsyncs to
operate again only in the original range, when using the NO_HOLES feature
and doing a fast fsync is doable but requires some non trivial changes to
the writeback path, which can always be worked on later if needed, but I
don't think they are a very common use case.
Several tests were performed using fio for different numbers of concurrent
jobs, each writing and fsyncing its own file, for both sequential and
random file writes. The tests were run on bare metal, no virtualization,
on a box with 12 cores (Intel i7-8700), 64Gb of RAM and a NVMe device,
with a kernel configuration that is the default of typical distributions
(debian in this case), without debug options enabled (kasan, kmemleak,
slub debug, debug of page allocations, lock debugging, etc).
The following script that calls fio was used:
$ cat test-fsync.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/btrfs
MOUNT_OPTIONS="-o ssd -o space_cache=v2"
MKFS_OPTIONS="-d single -m single"
if [ $# -ne 5 ]; then
echo "Use $0 NUM_JOBS FILE_SIZE FSYNC_FREQ BLOCK_SIZE [write|randwrite]"
exit 1
fi
NUM_JOBS=$1
FILE_SIZE=$2
FSYNC_FREQ=$3
BLOCK_SIZE=$4
WRITE_MODE=$5
if [ "$WRITE_MODE" != "write" ] && [ "$WRITE_MODE" != "randwrite" ]; then
echo "Invalid WRITE_MODE, must be 'write' or 'randwrite'"
exit 1
fi
cat <<EOF > /tmp/fio-job.ini
[writers]
rw=$WRITE_MODE
fsync=$FSYNC_FREQ
fallocate=none
group_reporting=1
direct=0
bs=$BLOCK_SIZE
ioengine=sync
size=$FILE_SIZE
directory=$MNT
numjobs=$NUM_JOBS
EOF
echo "performance" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
echo
echo "Using config:"
echo
cat /tmp/fio-job.ini
echo
umount $MNT &> /dev/null
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
fio /tmp/fio-job.ini
umount $MNT
The results were the following:
*************************
*** sequential writes ***
*************************
==== 1 job, 8GiB file, fsync frequency 1, block size 64KiB ====
Before patch:
WRITE: bw=36.6MiB/s (38.4MB/s), 36.6MiB/s-36.6MiB/s (38.4MB/s-38.4MB/s), io=8192MiB (8590MB), run=223689-223689msec
After patch:
WRITE: bw=40.2MiB/s (42.1MB/s), 40.2MiB/s-40.2MiB/s (42.1MB/s-42.1MB/s), io=8192MiB (8590MB), run=203980-203980msec
(+9.8%, -8.8% runtime)
==== 2 jobs, 4GiB files, fsync frequency 1, block size 64KiB ====
Before patch:
WRITE: bw=35.8MiB/s (37.5MB/s), 35.8MiB/s-35.8MiB/s (37.5MB/s-37.5MB/s), io=8192MiB (8590MB), run=228950-228950msec
After patch:
WRITE: bw=43.5MiB/s (45.6MB/s), 43.5MiB/s-43.5MiB/s (45.6MB/s-45.6MB/s), io=8192MiB (8590MB), run=188272-188272msec
(+21.5% throughput, -17.8% runtime)
==== 4 jobs, 2GiB files, fsync frequency 1, block size 64KiB ====
Before patch:
WRITE: bw=50.1MiB/s (52.6MB/s), 50.1MiB/s-50.1MiB/s (52.6MB/s-52.6MB/s), io=8192MiB (8590MB), run=163446-163446msec
After patch:
WRITE: bw=64.5MiB/s (67.6MB/s), 64.5MiB/s-64.5MiB/s (67.6MB/s-67.6MB/s), io=8192MiB (8590MB), run=126987-126987msec
(+28.7% throughput, -22.3% runtime)
==== 8 jobs, 1GiB files, fsync frequency 1, block size 64KiB ====
Before patch:
WRITE: bw=64.0MiB/s (68.1MB/s), 64.0MiB/s-64.0MiB/s (68.1MB/s-68.1MB/s), io=8192MiB (8590MB), run=126075-126075msec
After patch:
WRITE: bw=86.8MiB/s (91.0MB/s), 86.8MiB/s-86.8MiB/s (91.0MB/s-91.0MB/s), io=8192MiB (8590MB), run=94358-94358msec
(+35.6% throughput, -25.2% runtime)
==== 16 jobs, 512MiB files, fsync frequency 1, block size 64KiB ====
Before patch:
WRITE: bw=79.8MiB/s (83.6MB/s), 79.8MiB/s-79.8MiB/s (83.6MB/s-83.6MB/s), io=8192MiB (8590MB), run=102694-102694msec
After patch:
WRITE: bw=107MiB/s (112MB/s), 107MiB/s-107MiB/s (112MB/s-112MB/s), io=8192MiB (8590MB), run=76446-76446msec
(+34.1% throughput, -25.6% runtime)
==== 32 jobs, 512MiB files, fsync frequency 1, block size 64KiB ====
Before patch:
WRITE: bw=93.2MiB/s (97.7MB/s), 93.2MiB/s-93.2MiB/s (97.7MB/s-97.7MB/s), io=16.0GiB (17.2GB), run=175836-175836msec
After patch:
WRITE: bw=111MiB/s (117MB/s), 111MiB/s-111MiB/s (117MB/s-117MB/s), io=16.0GiB (17.2GB), run=147001-147001msec
(+19.1% throughput, -16.4% runtime)
==== 64 jobs, 512MiB files, fsync frequency 1, block size 64KiB ====
Before patch:
WRITE: bw=108MiB/s (114MB/s), 108MiB/s-108MiB/s (114MB/s-114MB/s), io=32.0GiB (34.4GB), run=302656-302656msec
After patch:
WRITE: bw=133MiB/s (140MB/s), 133MiB/s-133MiB/s (140MB/s-140MB/s), io=32.0GiB (34.4GB), run=246003-246003msec
(+23.1% throughput, -18.7% runtime)
************************
*** random writes ***
************************
==== 1 job, 8GiB file, fsync frequency 16, block size 4KiB ====
Before patch:
WRITE: bw=11.5MiB/s (12.0MB/s), 11.5MiB/s-11.5MiB/s (12.0MB/s-12.0MB/s), io=8192MiB (8590MB), run=714281-714281msec
After patch:
WRITE: bw=11.6MiB/s (12.2MB/s), 11.6MiB/s-11.6MiB/s (12.2MB/s-12.2MB/s), io=8192MiB (8590MB), run=705959-705959msec
(+0.9% throughput, -1.7% runtime)
==== 2 jobs, 4GiB files, fsync frequency 16, block size 4KiB ====
Before patch:
WRITE: bw=12.8MiB/s (13.5MB/s), 12.8MiB/s-12.8MiB/s (13.5MB/s-13.5MB/s), io=8192MiB (8590MB), run=638101-638101msec
After patch:
WRITE: bw=13.1MiB/s (13.7MB/s), 13.1MiB/s-13.1MiB/s (13.7MB/s-13.7MB/s), io=8192MiB (8590MB), run=625374-625374msec
(+2.3% throughput, -2.0% runtime)
==== 4 jobs, 2GiB files, fsync frequency 16, block size 4KiB ====
Before patch:
WRITE: bw=15.4MiB/s (16.2MB/s), 15.4MiB/s-15.4MiB/s (16.2MB/s-16.2MB/s), io=8192MiB (8590MB), run=531146-531146msec
After patch:
WRITE: bw=17.8MiB/s (18.7MB/s), 17.8MiB/s-17.8MiB/s (18.7MB/s-18.7MB/s), io=8192MiB (8590MB), run=460431-460431msec
(+15.6% throughput, -13.3% runtime)
==== 8 jobs, 1GiB files, fsync frequency 16, block size 4KiB ====
Before patch:
WRITE: bw=19.9MiB/s (20.8MB/s), 19.9MiB/s-19.9MiB/s (20.8MB/s-20.8MB/s), io=8192MiB (8590MB), run=412664-412664msec
After patch:
WRITE: bw=22.2MiB/s (23.3MB/s), 22.2MiB/s-22.2MiB/s (23.3MB/s-23.3MB/s), io=8192MiB (8590MB), run=368589-368589msec
(+11.6% throughput, -10.7% runtime)
==== 16 jobs, 512MiB files, fsync frequency 16, block size 4KiB ====
Before patch:
WRITE: bw=29.3MiB/s (30.7MB/s), 29.3MiB/s-29.3MiB/s (30.7MB/s-30.7MB/s), io=8192MiB (8590MB), run=279924-279924msec
After patch:
WRITE: bw=30.4MiB/s (31.9MB/s), 30.4MiB/s-30.4MiB/s (31.9MB/s-31.9MB/s), io=8192MiB (8590MB), run=269258-269258msec
(+3.8% throughput, -3.8% runtime)
==== 32 jobs, 512MiB files, fsync frequency 16, block size 4KiB ====
Before patch:
WRITE: bw=36.9MiB/s (38.7MB/s), 36.9MiB/s-36.9MiB/s (38.7MB/s-38.7MB/s), io=16.0GiB (17.2GB), run=443581-443581msec
After patch:
WRITE: bw=41.6MiB/s (43.6MB/s), 41.6MiB/s-41.6MiB/s (43.6MB/s-43.6MB/s), io=16.0GiB (17.2GB), run=394114-394114msec
(+12.7% throughput, -11.2% runtime)
==== 64 jobs, 512MiB files, fsync frequency 16, block size 4KiB ====
Before patch:
WRITE: bw=45.9MiB/s (48.1MB/s), 45.9MiB/s-45.9MiB/s (48.1MB/s-48.1MB/s), io=32.0GiB (34.4GB), run=714614-714614msec
After patch:
WRITE: bw=48.8MiB/s (51.1MB/s), 48.8MiB/s-48.8MiB/s (51.1MB/s-51.1MB/s), io=32.0GiB (34.4GB), run=672087-672087msec
(+6.3% throughput, -6.0% runtime)
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We're just doing rounding up to sectorsize to calculate the lockend.
There is no need to do the unnecessary length calculation, just direct
round_up() is enough.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-5.9-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
- fix swapfile activation on subvolumes with deleted snapshots
- error value mixup when removing directory entries from tree log
- fix lzo compression level reset after previous level setting
- fix space cache memory leak after transaction abort
- fix const function attribute
- more error handling improvements
* tag 'for-5.9-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: detect nocow for swap after snapshot delete
btrfs: check the right error variable in btrfs_del_dir_entries_in_log
btrfs: fix space cache memory leak after transaction abort
btrfs: use the correct const function attribute for btrfs_get_num_csums
btrfs: reset compression level for lzo on remount
btrfs: handle errors from async submission
can_nocow_extent and btrfs_cross_ref_exist both rely on a heuristic for
detecting a must cow condition which is not exactly accurate, but saves
unnecessary tree traversal. The incorrect assumption is that if the
extent was created in a generation smaller than the last snapshot
generation, it must be referenced by that snapshot. That is true, except
the snapshot could have since been deleted, without affecting the last
snapshot generation.
The original patch claimed a performance win from this check, but it
also leads to a bug where you are unable to use a swapfile if you ever
snapshotted the subvolume it's in. Make the check slower and more strict
for the swapon case, without modifying the general cow checks as a
compromise. Turning swap on does not seem to be a particularly
performance sensitive operation, so incurring a possibly unnecessary
btrfs_search_slot seems worthwhile for the added usability.
Note: Until the snapshot is competely cleaned after deletion,
check_committed_refs will still cause the logic to think that cow is
necessary, so the user must until 'btrfs subvolu sync' finished before
activating the swapfile swapon.
CC: stable@vger.kernel.org # 5.4+
Suggested-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-5.9/io_uring-20200802' of git://git.kernel.dk/linux-block
Pull io_uring updates from Jens Axboe:
"Lots of cleanups in here, hardening the code and/or making it easier
to read and fixing bugs, but a core feature/change too adding support
for real async buffered reads. With the latter in place, we just need
buffered write async support and we're done relying on kthreads for
the fast path. In detail:
- Cleanup how memory accounting is done on ring setup/free (Bijan)
- sq array offset calculation fixup (Dmitry)
- Consistently handle blocking off O_DIRECT submission path (me)
- Support proper async buffered reads, instead of relying on kthread
offload for that. This uses the page waitqueue to drive retries
from task_work, like we handle poll based retry. (me)
- IO completion optimizations (me)
- Fix race with accounting and ring fd install (me)
- Support EPOLLEXCLUSIVE (Jiufei)
- Get rid of the io_kiocb unionizing, made possible by shrinking
other bits (Pavel)
- Completion side cleanups (Pavel)
- Cleanup REQ_F_ flags handling, and kill off many of them (Pavel)
- Request environment grabbing cleanups (Pavel)
- File and socket read/write cleanups (Pavel)
- Improve kiocb_set_rw_flags() (Pavel)
- Tons of fixes and cleanups (Pavel)
- IORING_SQ_NEED_WAKEUP clear fix (Xiaoguang)"
* tag 'for-5.9/io_uring-20200802' of git://git.kernel.dk/linux-block: (127 commits)
io_uring: flip if handling after io_setup_async_rw
fs: optimise kiocb_set_rw_flags()
io_uring: don't touch 'ctx' after installing file descriptor
io_uring: get rid of atomic FAA for cq_timeouts
io_uring: consolidate *_check_overflow accounting
io_uring: fix stalled deferred requests
io_uring: fix racy overflow count reporting
io_uring: deduplicate __io_complete_rw()
io_uring: de-unionise io_kiocb
io-wq: update hash bits
io_uring: fix missing io_queue_linked_timeout()
io_uring: mark ->work uninitialised after cleanup
io_uring: deduplicate io_grab_files() calls
io_uring: don't do opcode prep twice
io_uring: clear IORING_SQ_NEED_WAKEUP after executing task works
io_uring: batch put_task_struct()
tasks: add put_task_struct_many()
io_uring: return locked and pinned page accounting
io_uring: don't miscount pinned memory
io_uring: don't open-code recv kbuf managment
...
Instead of calling BTRFS_I on the passed vfs_inode take btrfs_inode
directly.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It needs btrfs_inode so take it as a parameter directly.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It only uses btrfs_inode internally so take it as a parameter.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There's only a single use of vfs_inode in a tracepoint so let's take
btrfs_inode directly.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There is a single use of the generic vfs_inode so let's take btrfs_inode
as a parameter and remove couple of redundant BTRFS_I() calls.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Preparation to make btrfs_dirty_pages take btrfs_inode as parameter.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The function btrfs_check_can_nocow() now has two completely different
call patterns.
For nowait variant, callers don't need to do any cleanup. While for
wait variant, callers need to release the lock if they can do nocow
write.
This is somehow confusing, and is already a problem for the exported
btrfs_check_can_nocow().
So this patch will separate the different patterns into different
functions.
For nowait variant, the function will be called check_nocow_nolock().
For wait variant, the function pair will be btrfs_check_nocow_lock()
btrfs_check_nocow_unlock().
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
These two functions have extra conditions that their callers need to
meet, and some not-that-common parameters used for return value.
So adding some comments may save reviewers some time.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When the data space is exhausted, even if the inode has NOCOW attribute,
we will still refuse to truncate unaligned range due to ENOSPC.
The following script can reproduce it pretty easily:
#!/bin/bash
dev=/dev/test/test
mnt=/mnt/btrfs
umount $dev &> /dev/null
umount $mnt &> /dev/null
mkfs.btrfs -f $dev -b 1G
mount -o nospace_cache $dev $mnt
touch $mnt/foobar
chattr +C $mnt/foobar
xfs_io -f -c "pwrite -b 4k 0 4k" $mnt/foobar > /dev/null
xfs_io -f -c "pwrite -b 4k 0 1G" $mnt/padding &> /dev/null
sync
xfs_io -c "fpunch 0 2k" $mnt/foobar
umount $mnt
Currently this will fail at the fpunch part.
[CAUSE]
Because btrfs_truncate_block() always reserves space without checking
the NOCOW attribute.
Since the writeback path follows NOCOW bit, we only need to bother the
space reservation code in btrfs_truncate_block().
[FIX]
Make btrfs_truncate_block() follow btrfs_buffered_write() to try to
reserve data space first, and fall back to NOCOW check only when we
don't have enough space.
Such always-try-reserve is an optimization introduced in
btrfs_buffered_write(), to avoid expensive btrfs_check_can_nocow() call.
This patch will export check_can_nocow() as btrfs_check_can_nocow(), and
use it in btrfs_truncate_block() to fix the problem.
Reported-by: Martin Doucha <martin.doucha@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It has only 4 uses of a vfs_inode for inode_sub_bytes but unifies the
interface with the non __ prefixed version. Will also makes converting
its callers to btrfs_inode easier.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The incoming qgroup reserved space timing will move the data reservation
to ordered extent completely.
However in btrfs_punch_hole_lock_range() will call
btrfs_invalidate_page(), which will clear QGROUP_RESERVED bit for the
range.
In current stage it's OK, but if we're making ordered extents handle the
reserved space, then btrfs_punch_hole_lock_range() can clear the
QGROUP_RESERVED bit before we submit ordered extent, leading to qgroup
reserved space leakage.
So here change the timing to make reserve data space after
btrfs_punch_hole_lock_range().
The new timing is fine for either current code or the new code.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The call to btrfs_btree_balance_dirty has been there since the early
days of BTRFS, when the btree was directly modified from the write path,
hence dirtied btree inode pages. With the implementation of b888db2bd7
("Btrfs: Add delayed allocation to the extent based page tree code")
13 years ago the btree is no longer modified from the write path, hence
there is no point in calling this function. Just remove it.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs implements the iter_write op and thus can use the more efficient
iov_iter based splice implementation. For now falling back to the less
efficient default is pretty harmless, but I have a pending series that
removes the default, and thus would cause btrfs to not support splice
at all.
Reported-by: Andy Lavr <andy.lavr@gmail.com>
Tested-by: Andy Lavr <andy.lavr@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
A RWF_NOWAIT write is not supposed to wait on filesystem locks that can be
held for a long time or for ongoing IO to complete.
However when calling check_can_nocow(), if the inode has prealloc extents
or has the NOCOW flag set, we can block on extent (file range) locks
through the call to btrfs_lock_and_flush_ordered_range(). Such lock can
take a significant amount of time to be available. For example, a fiemap
task may be running, and iterating through the entire file range checking
all extents and doing backref walking to determine if they are shared,
or a readpage operation may be in progress.
Also at btrfs_lock_and_flush_ordered_range(), called by check_can_nocow(),
after locking the file range we wait for any existing ordered extent that
is in progress to complete. Another operation that can take a significant
amount of time and defeat the purpose of RWF_NOWAIT.
So fix this by trying to lock the file range and if it's currently locked
return -EAGAIN to user space. If we are able to lock the file range without
waiting and there is an ordered extent in the range, return -EAGAIN as
well, instead of waiting for it to complete. Finally, don't bother trying
to lock the snapshot lock of the root when attempting a RWF_NOWAIT write,
as that is only important for buffered writes.
Fixes: edf064e7c6 ("btrfs: nowait aio support")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we attempt to do a RWF_NOWAIT write against a file range for which we
can only do NOCOW for a part of it, due to the existence of holes or
shared extents for example, we proceed with the write as if it were
possible to NOCOW the whole range.
Example:
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
$ touch /mnt/sdj/bar
$ chattr +C /mnt/sdj/bar
$ xfs_io -d -c "pwrite -S 0xab -b 256K 0 256K" /mnt/bar
wrote 262144/262144 bytes at offset 0
256 KiB, 1 ops; 0.0003 sec (694.444 MiB/sec and 2777.7778 ops/sec)
$ xfs_io -c "fpunch 64K 64K" /mnt/bar
$ sync
$ xfs_io -d -c "pwrite -N -V 1 -b 128K -S 0xfe 0 128K" /mnt/bar
wrote 131072/131072 bytes at offset 0
128 KiB, 1 ops; 0.0007 sec (160.051 MiB/sec and 1280.4097 ops/sec)
This last write should fail with -EAGAIN since the file range from 64K to
128K is a hole. On xfs it fails, as expected, but on ext4 it currently
succeeds because apparently it is expensive to check if there are extents
allocated for the whole range, but I'll check with the ext4 people.
Fix the issue by checking if check_can_nocow() returns a number of
NOCOW'able bytes smaller then the requested number of bytes, and if it
does return -EAGAIN.
Fixes: edf064e7c6 ("btrfs: nowait aio support")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we do a successful RWF_NOWAIT write we end up locking the snapshot lock
of the inode, through a call to check_can_nocow(), but we never unlock it.
This means the next attempt to create a snapshot on the subvolume will
hang forever.
Trivial reproducer:
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
$ touch /mnt/foobar
$ chattr +C /mnt/foobar
$ xfs_io -d -c "pwrite -S 0xab 0 64K" /mnt/foobar
$ xfs_io -d -c "pwrite -N -V 1 -S 0xfe 0 64K" /mnt/foobar
$ btrfs subvolume snapshot -r /mnt /mnt/snap
--> hangs
Fix this by unlocking the snapshot lock if check_can_nocow() returned
success.
Fixes: edf064e7c6 ("btrfs: nowait aio support")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This reverts commit a43a67a2d7.
This patch reverts the main part of switching direct io implementation
to iomap infrastructure. There's a problem in invalidate page that
couldn't be solved as regression in this development cycle.
The problem occurs when buffered and direct io are mixed, and the ranges
overlap. Although this is not recommended, filesystems implement
measures or fallbacks to make it somehow work. In this case, fallback to
buffered IO would be an option for btrfs (this already happens when
direct io is done on compressed data), but the change would be needed in
the iomap code, bringing new semantics to other filesystems.
Another problem arises when again the buffered and direct ios are mixed,
invalidation fails, then -EIO is set on the mapping and fsync will fail,
though there's no real error.
There have been discussions how to fix that, but revert seems to be the
least intrusive option.
Link: https://lore.kernel.org/linux-btrfs/20200528192103.xm45qoxqmkw7i5yl@fiona/
Signed-off-by: David Sterba <dsterba@suse.com>
This reverts commit d8f3e73587.
The patch is a cleanup of direct IO port to iomap infrastructure,
which gets reverted.
Signed-off-by: David Sterba <dsterba@suse.com>
The read and write versions don't have anything in common except for the
call to iomap_dio_rw. So split this function, and merge each half into
its only caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Switch from __blockdev_direct_IO() to iomap_dio_rw().
Rename btrfs_get_blocks_direct() to btrfs_dio_iomap_begin() and use it
as iomap_begin() for iomap direct I/O functions. This function
allocates and locks all the blocks required for the I/O.
btrfs_submit_direct() is used as the submit_io() hook for direct I/O
ops.
Since we need direct I/O reads to go through iomap_dio_rw(), we change
file_operations.read_iter() to a btrfs_file_read_iter() which calls
btrfs_direct_IO() for direct reads and falls back to
generic_file_buffered_read() for incomplete reads and buffered reads.
We don't need address_space.direct_IO() anymore so set it to noop.
Similarly, we don't need flags used in __blockdev_direct_IO(). iomap is
capable of direct I/O reads from a hole, so we don't need to return
-ENOENT.
BTRFS direct I/O is now done under i_rwsem, shared in case of reads and
exclusive in case of writes. This guards against simultaneous truncates.
Use iomap->iomap_end() to check for failed or incomplete direct I/O:
- for writes, call __endio_write_update_ordered()
- for reads, unlock extents
btrfs_dio_data is now hooked in iomap->private and not
current->journal_info. It carries the reservation variable and the
amount of data submitted, so we can calculate the amount of data to call
__endio_write_update_ordered in case of an error.
This patch removes last use of struct buffer_head from btrfs.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The inode lookup starting at btrfs_iget takes the full location key,
while only the objectid is used to match the inode, because the lookup
happens inside the given root thus the inode number is unique.
The entire location key is properly set up in btrfs_init_locked_inode.
Simplify the helpers and pass only inode number, renaming it to 'ino'
instead of 'objectid'. This allows to remove temporary variables key,
saving some stack space.
Signed-off-by: David Sterba <dsterba@suse.com>
The main function to lookup a root by its id btrfs_get_fs_root takes the
whole key, while only using the objectid. The value of offset is preset
to (u64)-1 but not actually used until btrfs_find_root that does the
actual search.
Switch btrfs_get_fs_root to use only objectid and remove all local
variables that existed just for the lookup. The actual key for search is
set up in btrfs_get_fs_root, reusing another key variable.
Signed-off-by: David Sterba <dsterba@suse.com>
The name BTRFS_ROOT_REF_COWS is not very clear about the meaning.
In fact, that bit can only be set to those trees:
- Subvolume roots
- Data reloc root
- Reloc roots for above roots
All other trees won't get this bit set. So just by the result, it is
obvious that, roots with this bit set can have tree blocks shared with
other trees. Either shared by snapshots, or by reloc roots (an special
snapshot created by relocation).
This patch will rename BTRFS_ROOT_REF_COWS to BTRFS_ROOT_SHAREABLE to
make it easier to understand, and update all comment mentioning
"reference counted" to follow the rename.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is a revert of commit 0a8068a3dd ("btrfs: make ranged full
fsyncs more efficient"), with updated comment in btrfs_sync_file.
Commit 0a8068a3dd ("btrfs: make ranged full fsyncs more efficient")
made full fsyncs operate on the given range only as it assumed it was safe
when using the NO_HOLES feature, since the hole detection was simplified
some time ago and no longer was a source for races with ordered extent
completion of adjacent file ranges.
However it's still not safe to have a full fsync only operate on the given
range, because extent maps for new extents might not be present in memory
due to inode eviction or extent cloning. Consider the following example:
1) We are currently at transaction N;
2) We write to the file range [0, 1MiB);
3) Writeback finishes for the whole range and ordered extents complete,
while we are still at transaction N;
4) The inode is evicted;
5) We open the file for writing, causing the inode to be loaded to
memory again, which sets the 'full sync' bit on its flags. At this
point the inode's list of modified extent maps is empty (figuring
out which extents were created in the current transaction and were
not yet logged by an fsync is expensive, that's why we set the
'full sync' bit when loading an inode);
6) We write to the file range [512KiB, 768KiB);
7) We do a ranged fsync (such as msync()) for file range [512KiB, 768KiB).
This correctly flushes this range and logs its extent into the log
tree. When the writeback started an extent map for range [512KiB, 768KiB)
was added to the inode's list of modified extents, and when the fsync()
finishes logging it removes that extent map from the list of modified
extent maps. This fsync also clears the 'full sync' bit;
8) We do a regular fsync() (full ranged). This fsync() ends up doing
nothing because the inode's list of modified extents is empty and
no other changes happened since the previous ranged fsync(), so
it just returns success (0) and we end up never logging extents for
the file ranges [0, 512KiB) and [768KiB, 1MiB).
Another scenario where this can happen is if we replace steps 2 to 4 with
cloning from another file into our test file, as that sets the 'full sync'
bit in our inode's flags and does not populate its list of modified extent
maps.
This was causing test case generic/457 to fail sporadically when using the
NO_HOLES feature, as it exercised this later case where the inode has the
'full sync' bit set and has no extent maps in memory to represent the new
extents due to extent cloning.
Fix this by reverting commit 0a8068a3dd ("btrfs: make ranged full fsyncs
more efficient") since there is no easy way to work around it.
Fixes: 0a8068a3dd ("btrfs: make ranged full fsyncs more efficient")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Ordered ops are started twice in sync file, once outside of inode mutex
and once inside, taking the dio semaphore. There was one error path
missing the semaphore unlock.
Fixes: aab15e8ec2 ("Btrfs: fix rare chances for data loss when doing a fast fsync")
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Robbie Ko <robbieko@synology.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
[ add changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
Now that we have proper root ref counting everywhere we can kill the
subvol_srcu.
* removal of fs_info::subvol_srcu reduces size of fs_info by 1176 bytes
* the refcount_t used for the references checks for accidental 0->1
in cases where the root lifetime would not be properly protected
* there's a leak detector for roots to catch unfreed roots at umount
time
* SRCU served us well over the years but is was not a proper
synchronization mechanism for some cases
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
Commit 0c713cbab6 ("Btrfs: fix race between ranged fsync and writeback
of adjacent ranges") fixed a bug where we could end up with file extent
items in a log tree that represent file ranges that overlap due to a race
between the hole detection of a ranged full fsync and writeback for a
different file range.
The problem was solved by forcing any ranged full fsync to become a
non-ranged full fsync - setting the range start to 0 and the end offset to
LLONG_MAX. This was a simple solution because the code that detected and
marked holes was very complex, it used to be done at copy_items() and
implied several searches on the fs/subvolume tree. The drawback of that
solution was that we started to flush delalloc for the entire file and
wait for all the ordered extents to complete for ranged full fsyncs
(including ordered extents covering ranges completely outside the given
range). Fortunatelly ranged full fsyncs are not the most common case
(hopefully for most workloads).
However a later fix for detecting and marking holes was made by commit
0e56315ca1 ("Btrfs: fix missing hole after hole punching and fsync
when using NO_HOLES") and it simplified a lot the detection of holes,
and now copy_items() no longer does it and we do it in a much more simple
way at btrfs_log_holes().
This makes it now possible to simply make the code that detects holes to
operate only on the initial range and no longer need to operate on the
whole file, while also avoiding the need to flush delalloc for the entire
file and wait for ordered extents that cover ranges that don't overlap the
given range.
Another special care is that we must skip file extent items that fall
entirely outside the fsync range when copying inode items from the
fs/subvolume tree into the log tree - this is to avoid races with ordered
extent completion for extents falling outside the fsync range, which could
cause us to end up with file extent items in the log tree that have
overlapping ranges - for example if the fsync range is [1Mb, 2Mb], when
we copy inode items we could copy an extent item for the range [0, 512K],
then release the search path and before moving to the next leaf, an
ordered extent for a range of [256Kb, 512Kb] completes - this would
cause us to copy the new extent item for range [256Kb, 512Kb] into the
log tree after we have copied one for the range [0, 512Kb] - the extents
overlap, resulting in a corruption.
So this change just does these steps:
1) When the NO_HOLES feature is enabled it leaves the initial range
intact - no longer sets it to [0, LLONG_MAX] when the full sync bit
is set in the inode. If NO_HOLES is not enabled, always set the range
to a full, just like before this change, to avoid missing file extent
items representing holes after replaying the log (for both full and
fast fsyncs);
2) Make the hole detection code to operate only on the fsync range;
3) Make the code that copies items from the fs/subvolume tree to skip
copying file extent items that cover a range completely outside the
range of the fsync.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a fast fsync for a range that starts at an offset greater than
zero, we can end up with a log that when replayed causes the respective
inode miss a file extent item representing a hole if we are not using the
NO_HOLES feature. This is because for fast fsyncs we don't log any extents
that cover a range different from the one requested in the fsync.
Example scenario to trigger it:
$ mkfs.btrfs -O ^no-holes -f /dev/sdd
$ mount /dev/sdd /mnt
# Create a file with a single 256K and fsync it to clear to full sync
# bit in the inode - we want the msync below to trigger a fast fsync.
$ xfs_io -f -c "pwrite -S 0xab 0 256K" -c "fsync" /mnt/foo
# Force a transaction commit and wipe out the log tree.
$ sync
# Dirty 768K of data, increasing the file size to 1Mb, and flush only
# the range from 256K to 512K without updating the log tree
# (sync_file_range() does not trigger fsync, it only starts writeback
# and waits for it to finish).
$ xfs_io -c "pwrite -S 0xcd 256K 768K" /mnt/foo
$ xfs_io -c "sync_range -abw 256K 256K" /mnt/foo
# Now dirty the range from 768K to 1M again and sync that range.
$ xfs_io -c "mmap -w 768K 256K" \
-c "mwrite -S 0xef 768K 256K" \
-c "msync -s 768K 256K" \
-c "munmap" \
/mnt/foo
<power fail>
# Mount to replay the log.
$ mount /dev/sdd /mnt
$ umount /mnt
$ btrfs check /dev/sdd
Opening filesystem to check...
Checking filesystem on /dev/sdd
UUID: 482fb574-b288-478e-a190-a9c44a78fca6
[1/7] checking root items
[2/7] checking extents
[3/7] checking free space cache
[4/7] checking fs roots
root 5 inode 257 errors 100, file extent discount
Found file extent holes:
start: 262144, len: 524288
ERROR: errors found in fs roots
found 720896 bytes used, error(s) found
total csum bytes: 512
total tree bytes: 131072
total fs tree bytes: 32768
total extent tree bytes: 16384
btree space waste bytes: 123514
file data blocks allocated: 589824
referenced 589824
Fix this issue by setting the range to full (0 to LLONG_MAX) when the
NO_HOLES feature is not enabled. This results in extra work being done
but it gives the guarantee we don't end up with missing holes after
replaying the log.
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The reflink code is quite large and has been living in ioctl.c since ever.
It has grown over the years after many bug fixes and improvements, and
since I'm planning on making some further improvements on it, it's time
to get it better organized by moving into its own file, reflink.c
(similar to what xfs does for example).
This change only moves the code out of ioctl.c into the new file, it
doesn't do any other change.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This patch removes all haphazard code implementing nocow writers
exclusion from pending snapshot creation and switches to using the drew
lock to ensure this invariant still holds.
'Readers' are snapshot creators from create_snapshot and 'writers' are
nocow writers from buffered write path or btrfs_setsize. This locking
scheme allows for multiple snapshots to happen while any nocow writers
are blocked, since writes to page cache in the nocow path will make
snapshots inconsistent.
So for performance reasons we'd like to have the ability to run multiple
concurrent snapshots and also favors readers in this case. And in case
there aren't pending snapshots (which will be the majority of the cases)
we rely on the percpu's writers counter to avoid cacheline contention.
The main gain from using the drew lock is it's now a lot easier to
reason about the guarantees of the locking scheme and whether there is
some silent breakage lurking.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The tree pointer can be safely read from the inode so we can drop the
redundant argument from btrfs_lock_and_flush_ordered_range.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We are now using these for all roots, rename them to btrfs_put_root()
and btrfs_grab_root();
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that all callers of btrfs_get_fs_root are subsequently calling
btrfs_grab_fs_root and handling dropping the ref when they are done
appropriately, go ahead and push btrfs_grab_fs_root up into
btrfs_get_fs_root.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We are looking up an arbitrary inode, we need to hold a ref on the root
while we're doing this.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
All this does is call btrfs_get_fs_root() with check_ref == true. Just
use btrfs_get_fs_root() so we don't have a bunch of different helpers
that do the same thing.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that we have a safe way to update the i_size, replace all uses of
btrfs_ordered_update_i_size with btrfs_inode_safe_disk_i_size_write.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We want to use this everywhere we modify the file extent items
permanently. These include:
1) Inserting new file extents for writes and prealloc extents.
2) Truncating inode items.
3) btrfs_cont_expand().
4) Insert inline extents.
5) Insert new extents from log replay.
6) Insert a new extent for clone, as it could be past i_size.
7) Hole punching
For hole punching in particular it might seem it's not necessary because
anybody extending would use btrfs_cont_expand, however there is a corner
that still can give us trouble. Start with an empty file and
fallocate KEEP_SIZE 1M-2M
We now have a 0 length file, and a hole file extent from 0-1M, and a
prealloc extent from 1M-2M. Now
punch 1M-1.5M
Because this is past i_size we have
[HOLE EXTENT][ NOTHING ][PREALLOC]
[0 1M][1M 1.5M][1.5M 2M]
with an i_size of 0. Now if we pwrite 0-1.5M we'll increas our i_size
to 1.5M, but our disk_i_size is still 0 until the ordered extent
completes.
However if we now immediately truncate 2M on the file we'll just call
btrfs_cont_expand(inode, 1.5M, 2M), since our old i_size is 1.5M. If we
commit the transaction here and crash we'll expose the gap.
To fix this we need to clear the file extent mapping for the range that
we punched but didn't insert a corresponding file extent for. This will
mean the truncate will only get an disk_i_size set to 1M if we crash
before the finish ordered io happens.
I've written an xfstest to reproduce the problem and validate this fix.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We only pass this as 1 from __extent_writepage_io(). The parameter
basically means "pretend I didn't pass in a page". This is silly since
we can simply not pass in the page. Get rid of the parameter from
btrfs_get_extent(), and since it's used as a get_extent_t callback,
remove it from get_extent_t and btree_get_extent(), neither of which
need it.
While we're here, let's document btrfs_get_extent().
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
ordered->start, ordered->len, and ordered->disk_len correspond to
fi->disk_bytenr, fi->num_bytes, and fi->disk_num_bytes, respectively.
It's confusing to translate between the two naming schemes. Since a
btrfs_ordered_extent is basically a pending btrfs_file_extent_item,
let's make the former use the naming from the latter.
Note that I didn't touch the names in tracepoints just in case there are
scripts depending on the current naming.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When using the NO_HOLES feature if we clone a range that contains a hole
and a temporary ENOSPC happens while dropping extents from the target
inode's range, we can end up failing and aborting the transaction with
-EEXIST or with a corrupt file extent item, that has a length greater
than it should and overlaps with other extents. For example when cloning
the following range from inode A to inode B:
Inode A:
extent A1 extent A2
[ ----------- ] [ hole, implicit, 4MB length ] [ ------------- ]
0 1MB 5MB 6MB
Range to clone: [1MB, 6MB)
Inode B:
extent B1 extent B2 extent B3 extent B4
[ ---------- ] [ --------- ] [ ---------- ] [ ---------- ]
0 1MB 1MB 2MB 2MB 5MB 5MB 6MB
Target range: [1MB, 6MB) (same as source, to make it easier to explain)
The following can happen:
1) btrfs_punch_hole_range() gets -ENOSPC from __btrfs_drop_extents();
2) At that point, 'cur_offset' is set to 1MB and __btrfs_drop_extents()
set 'drop_end' to 2MB, meaning it was able to drop only extent B2;
3) We then compute 'clone_len' as 'drop_end' - 'cur_offset' = 2MB - 1MB =
1MB;
4) We then attempt to insert a file extent item at inode B with a file
offset of 5MB, which is the value of clone_info->file_offset. This
fails with error -EEXIST because there's already an extent at that
offset (extent B4);
5) We abort the current transaction with -EEXIST and return that error
to user space as well.
Another example, for extent corruption:
Inode A:
extent A1 extent A2
[ ----------- ] [ hole, implicit, 10MB length ] [ ------------- ]
0 1MB 11MB 12MB
Inode B:
extent B1 extent B2
[ ----------- ] [ --------- ] [ ----------------------------- ]
0 1MB 1MB 5MB 5MB 12MB
Target range: [1MB, 12MB) (same as source, to make it easier to explain)
1) btrfs_punch_hole_range() gets -ENOSPC from __btrfs_drop_extents();
2) At that point, 'cur_offset' is set to 1MB and __btrfs_drop_extents()
set 'drop_end' to 5MB, meaning it was able to drop only extent B2;
3) We then compute 'clone_len' as 'drop_end' - 'cur_offset' = 5MB - 1MB =
4MB;
4) We then insert a file extent item at inode B with a file offset of 11MB
which is the value of clone_info->file_offset, and a length of 4MB (the
value of 'clone_len'). So we get 2 extents items with ranges that
overlap and an extent length of 4MB, larger then the extent A2 from
inode A (1MB length);
5) After that we end the transaction, balance the btree dirty pages and
then start another or join the previous transaction. It might happen
that the transaction which inserted the incorrect extent was committed
by another task so we end up with extent corruption if a power failure
happens.
So fix this by making sure we attempt to insert the extent to clone at
the destination inode only if we are past dropping the sub-range that
corresponds to a hole.
Fixes: 690a5dbfc5 ("Btrfs: fix ENOSPC errors, leading to transaction aborts, when cloning extents")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We can now remove the bdev from extent_map. Previous patches made sure
that bio_set_dev is correctly in all places and that we don't need to
grab it from latest_bdev or pass it around inside the extent map.
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of using an input pointer parameter as the return value and have
an int as the return type of find_desired_extent, rework the function to
directly return the found offset. Doing that the 'ret' variable in
btrfs_llseek_file can be removed. Additional (subjective) benefit is
that btrfs' llseek function now resemebles those of the other major
filesystems.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Handle SEEK_END/SEEK_CUR in a single 'default' case by directly
returning from generic_file_llseek. This makes the 'out' label
redundant. Finally return directly the vale from vfs_setpos. No
semantic changes.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Modifying the file position is done on a per-file basis. This renders
holding the inode lock for writing useless and makes the performance of
concurrent llseek's abysmal.
Fix this by holding the inode for read. This provides protection against
concurrent truncates and find_desired_extent already includes proper
extent locking for the range which ensures proper locking against
concurrent writes. SEEK_CUR and SEEK_END can be done lockessly.
The former is synchronized by file::f_lock spinlock. SEEK_END is not
synchronized but atomic, but that's OK since there is not guarantee that
SEEK_END will always be at the end of the file in the face of tail
modifications.
This change brings ~82% performance improvement when doing a lot of
parallel fseeks. The workload essentially does:
for (d=0; d<num_seek_read; d++)
{
/* offset %= 16777216; */
fseek (f, 256 * d % 16777216, SEEK_SET);
fread (buffer, 64, 1, f);
}
Without patch:
num workprocesses = 16
num fseek/fread = 8000000
step = 256
fork 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
real 0m41.412s
user 0m28.777s
sys 2m16.510s
With patch:
num workprocesses = 16
num fseek/fread = 8000000
step = 256
fork 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
real 0m11.479s
user 0m27.629s
sys 0m21.040s
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a buffered write it's possible to leave the subv_writers
counter of the root, used for synchronization between buffered nocow
writers and snapshotting. This happens in an exceptional case like the
following:
1) We fail to allocate data space for the write, since there's not
enough available data space nor enough unallocated space for allocating
a new data block group;
2) Because of that failure, we try to go to NOCOW mode, which succeeds
and therefore we set the local variable 'only_release_metadata' to true
and set the root's sub_writers counter to 1 through the call to
btrfs_start_write_no_snapshotting() made by check_can_nocow();
3) The call to btrfs_copy_from_user() returns zero, which is very unlikely
to happen but not impossible;
4) No pages are copied because btrfs_copy_from_user() returned zero;
5) We call btrfs_end_write_no_snapshotting() which decrements the root's
subv_writers counter to 0;
6) We don't set 'only_release_metadata' back to 'false' because we do
it only if 'copied', the value returned by btrfs_copy_from_user(), is
greater than zero;
7) On the next iteration of the while loop, which processes the same
page range, we are now able to allocate data space for the write (we
got enough data space released in the meanwhile);
8) After this if we fail at btrfs_delalloc_reserve_metadata(), because
now there isn't enough free metadata space, or in some other place
further below (prepare_pages(), lock_and_cleanup_extent_if_need(),
btrfs_dirty_pages()), we break out of the while loop with
'only_release_metadata' having a value of 'true';
9) Because 'only_release_metadata' is 'true' we end up decrementing the
root's subv_writers counter to -1 (through a call to
btrfs_end_write_no_snapshotting()), and we also end up not releasing the
data space previously reserved through btrfs_check_data_free_space().
As a consequence the mechanism for synchronizing NOCOW buffered writes
with snapshotting gets broken.
Fix this by always setting 'only_release_metadata' to false at the start
of each iteration.
Fixes: 8257b2dc3c ("Btrfs: introduce btrfs_{start, end}_nocow_write() for each subvolume")
Fixes: 7ee9e4405f ("Btrfs: check if we can nocow if we don't have data space")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The parameter is now always set to NULL and could be dropped. The last
user was get_default_root but that got reworked in 05dbe6837b ("Btrfs:
unify subvol= and subvolid= mounting") and the parameter became unused.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is similar to 942491c9e6 ("xfs: fix AIM7 regression"). Apparently
our current rwsem code doesn't like doing the trylock, then lock for
real scheme. This causes extra contention on the lock and can be
measured eg. by AIM7 benchmark. So change our read/write methods to
just do the trylock for the RWF_NOWAIT case.
Fixes: edf064e7c6 ("btrfs: nowait aio support")
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
We were checking for the full fsync flag in the inode before locking the
inode, which is racy, since at that that time it might not be set but
after we acquire the inode lock some other task set it. One case where
this can happen is on a system low on memory and some concurrent task
failed to allocate an extent map and therefore set the full sync flag on
the inode, to force the next fsync to work in full mode.
A consequence of missing the full fsync flag set is hitting the problems
fixed by commit 0c713cbab6 ("Btrfs: fix race between ranged fsync and
writeback of adjacent ranges"), BUG_ON() when dropping extents from a log
tree, hitting assertion failures at tree-log.c:copy_items() or all sorts
of weird inconsistencies after replaying a log due to file extents items
representing ranges that overlap.
So just move the check such that it's done after locking the inode and
before starting writeback again.
Fixes: 0c713cbab6 ("Btrfs: fix race between ranged fsync and writeback of adjacent ranges")
CC: stable@vger.kernel.org # 5.2+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[Background]
Btrfs qgroup uses two types of reserved space for METADATA space,
PERTRANS and PREALLOC.
PERTRANS is metadata space reserved for each transaction started by
btrfs_start_transaction().
While PREALLOC is for delalloc, where we reserve space before joining a
transaction, and finally it will be converted to PERTRANS after the
writeback is done.
[Inconsistency]
However there is inconsistency in how we handle PREALLOC metadata space.
The most obvious one is:
In btrfs_buffered_write():
btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes, true);
We always free qgroup PREALLOC meta space.
While in btrfs_truncate_block():
btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize, (ret != 0));
We only free qgroup PREALLOC meta space when something went wrong.
[The Correct Behavior]
The correct behavior should be the one in btrfs_buffered_write(), we
should always free PREALLOC metadata space.
The reason is, the btrfs_delalloc_* mechanism works by:
- Reserve metadata first, even it's not necessary
In btrfs_delalloc_reserve_metadata()
- Free the unused metadata space
Normally in:
btrfs_delalloc_release_extents()
|- btrfs_inode_rsv_release()
Here we do calculation on whether we should release or not.
E.g. for 64K buffered write, the metadata rsv works like:
/* The first page */
reserve_meta: num_bytes=calc_inode_reservations()
free_meta: num_bytes=0
total: num_bytes=calc_inode_reservations()
/* The first page caused one outstanding extent, thus needs metadata
rsv */
/* The 2nd page */
reserve_meta: num_bytes=calc_inode_reservations()
free_meta: num_bytes=calc_inode_reservations()
total: not changed
/* The 2nd page doesn't cause new outstanding extent, needs no new meta
rsv, so we free what we have reserved */
/* The 3rd~16th pages */
reserve_meta: num_bytes=calc_inode_reservations()
free_meta: num_bytes=calc_inode_reservations()
total: not changed (still space for one outstanding extent)
This means, if btrfs_delalloc_release_extents() determines to free some
space, then those space should be freed NOW.
So for qgroup, we should call btrfs_qgroup_free_meta_prealloc() other
than btrfs_qgroup_convert_reserved_meta().
The good news is:
- The callers are not that hot
The hottest caller is in btrfs_buffered_write(), which is already
fixed by commit 336a8bb8e3 ("btrfs: Fix wrong
btrfs_delalloc_release_extents parameter"). Thus it's not that
easy to cause false EDQUOT.
- The trans commit in advance for qgroup would hide the bug
Since commit f5fef45936 ("btrfs: qgroup: Make qgroup async transaction
commit more aggressive"), when btrfs qgroup metadata free space is slow,
it will try to commit transaction and free the wrongly converted
PERTRANS space, so it's not that easy to hit such bug.
[FIX]
So to fix the problem, remove the @qgroup_free parameter for
btrfs_delalloc_release_extents(), and always pass true to
btrfs_inode_rsv_release().
Reported-by: Filipe Manana <fdmanana@suse.com>
Fixes: 43b18595d6 ("btrfs: qgroup: Use separate meta reservation type for delalloc")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we have a buffered write that starts at an offset greater than or
equals to the file's size happening concurrently with a full ranged
fiemap, we can end up leaking an extent state structure.
Suppose we have a file with a size of 1Mb, and before the buffered write
and fiemap are performed, it has a single extent state in its io tree
representing the range from 0 to 1Mb, with the EXTENT_DELALLOC bit set.
The following sequence diagram shows how the memory leak happens if a
fiemap a buffered write, starting at offset 1Mb and with a length of
4Kb, are performed concurrently.
CPU 1 CPU 2
extent_fiemap()
--> it's a full ranged fiemap
range from 0 to LLONG_MAX - 1
(9223372036854775807)
--> locks range in the inode's
io tree
--> after this we have 2 extent
states in the io tree:
--> 1 for range [0, 1Mb[ with
the bits EXTENT_LOCKED and
EXTENT_DELALLOC_BITS set
--> 1 for the range
[1Mb, LLONG_MAX[ with
the EXTENT_LOCKED bit set
--> start buffered write at offset
1Mb with a length of 4Kb
btrfs_file_write_iter()
btrfs_buffered_write()
--> cached_state is NULL
lock_and_cleanup_extent_if_need()
--> returns 0 and does not lock
range because it starts
at current i_size / eof
--> cached_state remains NULL
btrfs_dirty_pages()
btrfs_set_extent_delalloc()
(...)
__set_extent_bit()
--> splits extent state for range
[1Mb, LLONG_MAX[ and now we
have 2 extent states:
--> one for the range
[1Mb, 1Mb + 4Kb[ with
EXTENT_LOCKED set
--> another one for the range
[1Mb + 4Kb, LLONG_MAX[ with
EXTENT_LOCKED set as well
--> sets EXTENT_DELALLOC on the
extent state for the range
[1Mb, 1Mb + 4Kb[
--> caches extent state
[1Mb, 1Mb + 4Kb[ into
@cached_state because it has
the bit EXTENT_LOCKED set
--> btrfs_buffered_write() ends up
with a non-NULL cached_state and
never calls anything to release its
reference on it, resulting in a
memory leak
Fix this by calling free_extent_state() on cached_state if the range was
not locked by lock_and_cleanup_extent_if_need().
The same issue can happen if anything else other than fiemap locks a range
that covers eof and beyond.
This could be triggered, sporadically, by test case generic/561 from the
fstests suite, which makes duperemove run concurrently with fsstress, and
duperemove does plenty of calls to fiemap. When CONFIG_BTRFS_DEBUG is set
the leak is reported in dmesg/syslog when removing the btrfs module with
a message like the following:
[77100.039461] BTRFS: state leak: start 6574080 end 6582271 state 16402 in tree 0 refs 1
Otherwise (CONFIG_BTRFS_DEBUG not set) detectable with kmemleak.
CC: stable@vger.kernel.org # 4.16+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Since commit fee187d9d9 ("Btrfs: do not set EXTENT_DIRTY along with
EXTENT_DELALLOC"), we never set EXTENT_DIRTY in inode->io_tree, so we
can simplify and stop trying to clear it.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The VFS indicates a synchronous write to ->write_iter() via
iocb->ki_flags. The IOCB_{,D}SYNC flags may be set based on the file
(see iocb_flags()) or the RWF_* flags passed to a syscall like
pwritev2() (see kiocb_set_rw_flags()).
However, in btrfs_file_write_iter(), we're checking if a write is
synchronous based only on the file; we use this to decide when to bump
the sync_writers counter and thus do CRCs synchronously. Make sure we do
this for all synchronous writes as determined by the VFS.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add const ]
Signed-off-by: David Sterba <dsterba@suse.com>
generic_write_checks() may modify iov_iter_count(), so we must get the
count after the call, not before. Using the wrong one has a couple of
consequences:
1. We check a longer range in check_can_nocow() for nowait than we're
actually writing.
2. We create extra hole extent maps in btrfs_cont_expand(). As far as I
can tell, this is harmless, but I might be missing something.
These issues are pretty minor, but let's fix it before something more
important trips on it.
Fixes: edf064e7c6 ("btrfs: nowait aio support")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_calc_trunc_metadata_size differs from trans_metadata_size in that
it doesn't take into account any splitting at the levels, because
truncate will never split nodes. However truncate _and_ changing will
never split nodes, so rename btrfs_calc_trunc_metadata_size to
btrfs_calc_metadata_size. Also btrfs_calc_trans_metadata_size is purely
for inserting items, so rename this to btrfs_calc_insert_metadata_size.
Making these clearer will help when I start using them differently in
upcoming patches.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It's unlikely in-band dedupe is going to land so just remove any
leftovers - dedupe.h header as well as the 'dedupe' parameter to
btrfs_set_extent_delalloc.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When cloning extents (or deduplicating) we create a transaction with a
space reservation that considers we will drop or update a single file
extent item of the destination inode (that we modify a single leaf). That
is fine for the vast majority of scenarios, however it might happen that
we need to drop many file extent items, and adjust at most two file extent
items, in the destination root, which can span multiple leafs. This will
lead to either the call to btrfs_drop_extents() to fail with ENOSPC or
the subsequent calls to btrfs_insert_empty_item() or btrfs_update_inode()
(called through clone_finish_inode_update()) to fail with ENOSPC. Such
failure results in a transaction abort, leaving the filesystem in a
read-only mode.
In order to fix this we need to follow the same approach as the hole
punching code, where we create a local reservation with 1 unit and keep
ending and starting transactions, after balancing the btree inode,
when __btrfs_drop_extents() returns ENOSPC. So fix this by making the
extent cloning call calls the recently added btrfs_punch_hole_range()
helper, which is what does the mentioned work for hole punching, and
make sure whenever we drop extent items in a transaction, we also add a
replacing file extent item, to avoid corruption (a hole) if after ending
a transaction and before starting a new one, the old transaction gets
committed and a power failure happens before we finish cloning.
A test case for fstests follows soon.
Reported-by: David Goodwin <david@codepoets.co.uk>
Link: https://lore.kernel.org/linux-btrfs/a4a4cf31-9cf4-e52c-1f86-c62d336c9cd1@codepoets.co.uk/
Reported-by: Sam Tygier <sam@tygier.co.uk>
Link: https://lore.kernel.org/linux-btrfs/82aace9f-a1e3-1f0b-055f-3ea75f7a41a0@tygier.co.uk/
Fixes: b6f3409b21 ("Btrfs: reserve sufficient space for ioctl clone")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move the code that is responsible for dropping extents in a range out of
btrfs_punch_hole() into a new helper function, btrfs_punch_hole_range(),
so that later it can be used by the reflinking (extent cloning and dedup)
code to fix a ENOSPC bug.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have code for data and metadata reservations for delalloc. There's
quite a bit of code here, and it's used in a lot of places so I've
separated it out to it's own file. inode.c and file.c are already
pretty large, and this code is complicated enough to live in its own
space.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
A few more instances whre we don't need to specify the values as long as
they are the same that enum assigns automatically. All of the enums are
in-memory only and nothing relies on the exact values.
Signed-off-by: David Sterba <dsterba@suse.com>
If the range for which we are punching a hole covers only part of a page,
we end up updating the inode item but we skip the update of the inode's
iversion, mtime and ctime. Fix that by ensuring we update those properties
of the inode.
A patch for fstests test case generic/059 that tests this as been sent
along with this fix.
Fixes: 2aaa665581 ("Btrfs: add hole punching")
Fixes: e8c1c76e80 ("Btrfs: add missing inode update when punching hole")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The first thing code does in check_can_nocow is trying to block
concurrent snapshots. If this fails (due to snpashot already being in
progress) the function returns ENOSPC which makes no sense. Instead
return EAGAIN. Despite this return value not being propagated to callers
it's good practice to return the closest in terms of semantics error
code. No functional changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There several functions which open code
btrfs_lock_and_flush_ordered_range, just replace them with a call to the
function. No functional changes.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we do a full fsync (the bit BTRFS_INODE_NEEDS_FULL_SYNC is set in the
inode) that happens to be ranged, which happens during a msync() or writes
for files opened with O_SYNC for example, we can end up with a corrupt log,
due to different file extent items representing ranges that overlap with
each other, or hit some assertion failures.
When doing a ranged fsync we only flush delalloc and wait for ordered
exents within that range. If while we are logging items from our inode
ordered extents for adjacent ranges complete, we end up in a race that can
make us insert the file extent items that overlap with others we logged
previously and the assertion failures.
For example, if tree-log.c:copy_items() receives a leaf that has the
following file extents items, all with a length of 4K and therefore there
is an implicit hole in the range 68K to 72K - 1:
(257 EXTENT_ITEM 64K), (257 EXTENT_ITEM 72K), (257 EXTENT_ITEM 76K), ...
It copies them to the log tree. However due to the need to detect implicit
holes, it may release the path, in order to look at the previous leaf to
detect an implicit hole, and then later it will search again in the tree
for the first file extent item key, with the goal of locking again the
leaf (which might have changed due to concurrent changes to other inodes).
However when it locks again the leaf containing the first key, the key
corresponding to the extent at offset 72K may not be there anymore since
there is an ordered extent for that range that is finishing (that is,
somewhere in the middle of btrfs_finish_ordered_io()), and it just
removed the file extent item but has not yet replaced it with a new file
extent item, so the part of copy_items() that does hole detection will
decide that there is a hole in the range starting from 68K to 76K - 1,
and therefore insert a file extent item to represent that hole, having
a key offset of 68K. After that we now have a log tree with 2 different
extent items that have overlapping ranges:
1) The file extent item copied before copy_items() released the path,
which has a key offset of 72K and a length of 4K, representing the
file range 72K to 76K - 1.
2) And a file extent item representing a hole that has a key offset of
68K and a length of 8K, representing the range 68K to 76K - 1. This
item was inserted after releasing the path, and overlaps with the
extent item inserted before.
The overlapping extent items can cause all sorts of unpredictable and
incorrect behaviour, either when replayed or if a fast (non full) fsync
happens later, which can trigger a BUG_ON() when calling
btrfs_set_item_key_safe() through __btrfs_drop_extents(), producing a
trace like the following:
[61666.783269] ------------[ cut here ]------------
[61666.783943] kernel BUG at fs/btrfs/ctree.c:3182!
[61666.784644] invalid opcode: 0000 [#1] PREEMPT SMP
(...)
[61666.786253] task: ffff880117b88c40 task.stack: ffffc90008168000
[61666.786253] RIP: 0010:btrfs_set_item_key_safe+0x7c/0xd2 [btrfs]
[61666.786253] RSP: 0018:ffffc9000816b958 EFLAGS: 00010246
[61666.786253] RAX: 0000000000000000 RBX: 000000000000000f RCX: 0000000000030000
[61666.786253] RDX: 0000000000000000 RSI: ffffc9000816ba4f RDI: ffffc9000816b937
[61666.786253] RBP: ffffc9000816b998 R08: ffff88011dae2428 R09: 0000000000001000
[61666.786253] R10: 0000160000000000 R11: 6db6db6db6db6db7 R12: ffff88011dae2418
[61666.786253] R13: ffffc9000816ba4f R14: ffff8801e10c4118 R15: ffff8801e715c000
[61666.786253] FS: 00007f6060a18700(0000) GS:ffff88023f5c0000(0000) knlGS:0000000000000000
[61666.786253] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[61666.786253] CR2: 00007f6060a28000 CR3: 0000000213e69000 CR4: 00000000000006e0
[61666.786253] Call Trace:
[61666.786253] __btrfs_drop_extents+0x5e3/0xaad [btrfs]
[61666.786253] ? time_hardirqs_on+0x9/0x14
[61666.786253] btrfs_log_changed_extents+0x294/0x4e0 [btrfs]
[61666.786253] ? release_extent_buffer+0x38/0xb4 [btrfs]
[61666.786253] btrfs_log_inode+0xb6e/0xcdc [btrfs]
[61666.786253] ? lock_acquire+0x131/0x1c5
[61666.786253] ? btrfs_log_inode_parent+0xee/0x659 [btrfs]
[61666.786253] ? arch_local_irq_save+0x9/0xc
[61666.786253] ? btrfs_log_inode_parent+0x1f5/0x659 [btrfs]
[61666.786253] btrfs_log_inode_parent+0x223/0x659 [btrfs]
[61666.786253] ? arch_local_irq_save+0x9/0xc
[61666.786253] ? lockref_get_not_zero+0x2c/0x34
[61666.786253] ? rcu_read_unlock+0x3e/0x5d
[61666.786253] btrfs_log_dentry_safe+0x60/0x7b [btrfs]
[61666.786253] btrfs_sync_file+0x317/0x42c [btrfs]
[61666.786253] vfs_fsync_range+0x8c/0x9e
[61666.786253] SyS_msync+0x13c/0x1c9
[61666.786253] entry_SYSCALL_64_fastpath+0x18/0xad
A sample of a corrupt log tree leaf with overlapping extents I got from
running btrfs/072:
item 14 key (295 108 200704) itemoff 2599 itemsize 53
extent data disk bytenr 0 nr 0
extent data offset 0 nr 458752 ram 458752
item 15 key (295 108 659456) itemoff 2546 itemsize 53
extent data disk bytenr 4343541760 nr 770048
extent data offset 606208 nr 163840 ram 770048
item 16 key (295 108 663552) itemoff 2493 itemsize 53
extent data disk bytenr 4343541760 nr 770048
extent data offset 610304 nr 155648 ram 770048
item 17 key (295 108 819200) itemoff 2440 itemsize 53
extent data disk bytenr 4334788608 nr 4096
extent data offset 0 nr 4096 ram 4096
The file extent item at offset 659456 (item 15) ends at offset 823296
(659456 + 163840) while the next file extent item (item 16) starts at
offset 663552.
Another different problem that the race can trigger is a failure in the
assertions at tree-log.c:copy_items(), which expect that the first file
extent item key we found before releasing the path exists after we have
released path and that the last key we found before releasing the path
also exists after releasing the path:
$ cat -n fs/btrfs/tree-log.c
4080 if (need_find_last_extent) {
4081 /* btrfs_prev_leaf could return 1 without releasing the path */
4082 btrfs_release_path(src_path);
4083 ret = btrfs_search_slot(NULL, inode->root, &first_key,
4084 src_path, 0, 0);
4085 if (ret < 0)
4086 return ret;
4087 ASSERT(ret == 0);
(...)
4103 if (i >= btrfs_header_nritems(src_path->nodes[0])) {
4104 ret = btrfs_next_leaf(inode->root, src_path);
4105 if (ret < 0)
4106 return ret;
4107 ASSERT(ret == 0);
4108 src = src_path->nodes[0];
4109 i = 0;
4110 need_find_last_extent = true;
4111 }
(...)
The second assertion implicitly expects that the last key before the path
release still exists, because the surrounding while loop only stops after
we have found that key. When this assertion fails it produces a stack like
this:
[139590.037075] assertion failed: ret == 0, file: fs/btrfs/tree-log.c, line: 4107
[139590.037406] ------------[ cut here ]------------
[139590.037707] kernel BUG at fs/btrfs/ctree.h:3546!
[139590.038034] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
[139590.038340] CPU: 1 PID: 31841 Comm: fsstress Tainted: G W 5.0.0-btrfs-next-46 #1
(...)
[139590.039354] RIP: 0010:assfail.constprop.24+0x18/0x1a [btrfs]
(...)
[139590.040397] RSP: 0018:ffffa27f48f2b9b0 EFLAGS: 00010282
[139590.040730] RAX: 0000000000000041 RBX: ffff897c635d92c8 RCX: 0000000000000000
[139590.041105] RDX: 0000000000000000 RSI: ffff897d36a96868 RDI: ffff897d36a96868
[139590.041470] RBP: ffff897d1b9a0708 R08: 0000000000000000 R09: 0000000000000000
[139590.041815] R10: 0000000000000008 R11: 0000000000000000 R12: 0000000000000013
[139590.042159] R13: 0000000000000227 R14: ffff897cffcbba88 R15: 0000000000000001
[139590.042501] FS: 00007f2efc8dee80(0000) GS:ffff897d36a80000(0000) knlGS:0000000000000000
[139590.042847] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[139590.043199] CR2: 00007f8c064935e0 CR3: 0000000232252002 CR4: 00000000003606e0
[139590.043547] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[139590.043899] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[139590.044250] Call Trace:
[139590.044631] copy_items+0xa3f/0x1000 [btrfs]
[139590.045009] ? generic_bin_search.constprop.32+0x61/0x200 [btrfs]
[139590.045396] btrfs_log_inode+0x7b3/0xd70 [btrfs]
[139590.045773] btrfs_log_inode_parent+0x2b3/0xce0 [btrfs]
[139590.046143] ? do_raw_spin_unlock+0x49/0xc0
[139590.046510] btrfs_log_dentry_safe+0x4a/0x70 [btrfs]
[139590.046872] btrfs_sync_file+0x3b6/0x440 [btrfs]
[139590.047243] btrfs_file_write_iter+0x45b/0x5c0 [btrfs]
[139590.047592] __vfs_write+0x129/0x1c0
[139590.047932] vfs_write+0xc2/0x1b0
[139590.048270] ksys_write+0x55/0xc0
[139590.048608] do_syscall_64+0x60/0x1b0
[139590.048946] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[139590.049287] RIP: 0033:0x7f2efc4be190
(...)
[139590.050342] RSP: 002b:00007ffe743243a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[139590.050701] RAX: ffffffffffffffda RBX: 0000000000008d58 RCX: 00007f2efc4be190
[139590.051067] RDX: 0000000000008d58 RSI: 00005567eca0f370 RDI: 0000000000000003
[139590.051459] RBP: 0000000000000024 R08: 0000000000000003 R09: 0000000000008d60
[139590.051863] R10: 0000000000000078 R11: 0000000000000246 R12: 0000000000000003
[139590.052252] R13: 00000000003d3507 R14: 00005567eca0f370 R15: 0000000000000000
(...)
[139590.055128] ---[ end trace 193f35d0215cdeeb ]---
So fix this race between a full ranged fsync and writeback of adjacent
ranges by flushing all delalloc and waiting for all ordered extents to
complete before logging the inode. This is the simplest way to solve the
problem because currently the full fsync path does not deal with ranges
at all (it assumes a full range from 0 to LLONG_MAX) and it always needs
to look at adjacent ranges for hole detection. For use cases of ranged
fsyncs this can make a few fsyncs slower but on the other hand it can
make some following fsyncs to other ranges do less work or no need to do
anything at all. A full fsync is rare anyway and happens only once after
loading/creating an inode and once after less common operations such as a
shrinking truncate.
This is an issue that exists for a long time, and was often triggered by
generic/127, because it does mmap'ed writes and msync (which triggers a
ranged fsync). Adding support for the tree checker to detect overlapping
extents (next patch in the series) and trigger a WARN() when such cases
are found, and then calling btrfs_check_leaf_full() at the end of
btrfs_insert_file_extent() made the issue much easier to detect. Running
btrfs/072 with that change to the tree checker and making fsstress open
files always with O_SYNC made it much easier to trigger the issue (as
triggering it with generic/127 is very rare).
CC: stable@vger.kernel.org # 3.16+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we have an error writing out a delalloc range in
btrfs_punch_hole_lock_range we'll unlock the inode and then goto
out_only_mutex, where we will again unlock the inode. This is bad,
don't do this.
Fixes: f27451f229 ("Btrfs: add support for fallocate's zero range operation")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba