OpenCloudOS-Kernel/fs
Eric Whitney efc6134527 ext4: shrink race window in ext4_should_retry_alloc()
When generic/371 is run on kvm-xfstests using 5.10 and 5.11 kernels, it
fails at significant rates on the two test scenarios that disable
delayed allocation (ext3conv and data_journal) and force actual block
allocation for the fallocate and pwrite functions in the test.  The
failure rate on 5.10 for both ext3conv and data_journal on one test
system typically runs about 85%.  On 5.11, the failure rate on ext3conv
sometimes drops to as low as 1% while the rate on data_journal
increases to nearly 100%.

The observed failures are largely due to ext4_should_retry_alloc()
cutting off block allocation retries when s_mb_free_pending (used to
indicate that a transaction in progress will free blocks) is 0.
However, free space is usually available when this occurs during runs
of generic/371.  It appears that a thread attempting to allocate
blocks is just missing transaction commits in other threads that
increase the free cluster count and reset s_mb_free_pending while
the allocating thread isn't running.  Explicitly testing for free space
availability avoids this race.

The current code uses a post-increment operator in the conditional
expression that determines whether the retry limit has been exceeded.
This means that the conditional expression uses the value of the
retry counter before it's increased, resulting in an extra retry cycle.
The current code actually retries twice before hitting its retry limit
rather than once.

Increasing the retry limit to 3 from the current actual maximum retry
count of 2 in combination with the change described above reduces the
observed failure rate to less that 0.1% on both ext3conv and
data_journal with what should be limited impact on users sensitive to
the overhead caused by retries.

A per filesystem percpu counter exported via sysfs is added to allow
users or developers to track the number of times the retry limit is
exceeded without resorting to debugging methods.  This should provide
some insight into worst case retry behavior.

Signed-off-by: Eric Whitney <enwlinux@gmail.com>
Link: https://lore.kernel.org/r/20210218151132.19678-1-enwlinux@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-03-06 11:56:10 -05:00
..
9p Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-02-27 08:07:12 -08:00
adfs fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
affs idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
afs idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
autofs fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
befs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
bfs fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
btrfs for-5.12-rc1-tag 2021-03-05 12:21:14 -08:00
cachefiles idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
ceph idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
cifs cifs/smb3 fixes including improvements to mode bit conversion when using cifsacl mount option, new mount options for controlling attribute caching, improvements to crediting and reconnect, improved debugging 2021-02-26 14:09:41 -08:00
coda fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
configfs fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
cramfs cramfs: use %pD instead of messing with file_dentry()->d_name 2021-01-05 23:02:47 -05:00
crypto inode: make init and permission helpers idmapped mount aware 2021-01-24 14:27:16 +01:00
debugfs Driver core / debugfs update for 5.12-rc1 2021-02-24 10:13:55 -08:00
devpts
dlm fs: dlm: check on existing node address 2020-11-10 12:14:20 -06:00
ecryptfs idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
efivarfs fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
efs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
erofs block-5.12-2021-02-27 2021-02-28 11:23:38 -08:00
exfat idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
exportfs exportfs: Add a function to return the raw output from fh_to_dentry() 2020-12-09 09:39:38 -05:00
ext2 fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
ext4 ext4: shrink race window in ext4_should_retry_alloc() 2021-03-06 11:56:10 -05:00
f2fs block-5.12-2021-02-27 2021-02-28 11:23:38 -08:00
fat idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
freevxfs
fscache
fuse mm/filemap: remove unused parameter and change to void type for replace_page_cache_page() 2021-02-24 13:38:27 -08:00
gfs2 Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-02-27 08:07:12 -08:00
hfs fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
hfsplus idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
hostfs idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
hpfs fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
hugetlbfs hugetlbfs: remove unneeded return value of hugetlb_vmtruncate() 2021-02-24 13:38:35 -08:00
iomap More new code for 5.12: 2021-02-28 11:45:25 -08:00
isofs isofs: handle large user and group ID 2021-02-03 19:05:52 +01:00
jbd2 block: use an on-stack bio in blkdev_issue_flush 2021-01-27 09:51:48 -07:00
jffs2 idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
jfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-02-27 08:07:12 -08:00
kernfs idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
lockd SUNRPC: Make trace_svc_process() display the RPC procedure symbolically 2021-01-25 09:36:23 -05:00
minix fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
nfs block-5.12-2021-02-27 2021-02-28 11:23:38 -08:00
nfs_common NFSv4_2: SSC helper should use its own config. 2021-01-28 10:55:37 -05:00
nfsd idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
nilfs2 idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
nls
notify idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
ntfs ntfs: check for valid standard information attribute 2021-02-24 13:38:26 -08:00
ocfs2 ocfs2: simplify the calculation of variables 2021-02-24 13:38:26 -08:00
omfs fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
openpromfs
orangefs idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
overlayfs idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
proc io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
pstore pstore fixes for v5.12-rc2 2021-03-05 17:21:25 -08:00
qnx4 [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
qnx6 [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
quota quota: Fix memory leak when handling corrupted quota file 2021-01-05 14:42:18 +01:00
ramfs ramfs: support O_TMPFILE 2021-02-24 13:38:26 -08:00
reiserfs idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
romfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
squashfs squashfs: add more sanity checks in xattr id lookup 2021-02-09 17:26:44 -08:00
sysfs sysfs: Support zapping of binary attr mmaps 2021-01-12 14:26:31 +01:00
sysv fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
tracefs fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
ubifs idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
udf idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
ufs fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
unicode unicode: Add utf8_casefold_hash 2020-09-10 14:03:31 -07:00
vboxsf fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
verity idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
xfs More new code for 5.12: 2021-02-28 11:45:25 -08:00
zonefs idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
Kconfig Highlights: 2021-02-21 10:22:20 -08:00
Kconfig.binfmt Merge branch 'work.elf-compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-02-21 09:29:23 -08:00
Makefile fs: Remove dcookies support 2021-01-29 10:06:46 +05:30
aio.c Merge branch 'akpm' (patches from Andrew) 2020-12-15 12:53:37 -08:00
anon_inodes.c fs: anon_inodes: rephrase to appropriate kernel-doc 2021-01-15 12:17:25 -05:00
attr.c ima: handle idmapped mounts 2021-01-24 14:27:20 +01:00
bad_inode.c fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
binfmt_aout.c
binfmt_elf.c Merge branch 'parisc-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 2021-02-21 13:20:41 -08:00
binfmt_elf_fdpic.c Merge branch 'parisc-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 2021-02-21 13:20:41 -08:00
binfmt_em86.c
binfmt_flat.c binfmt_flat: revert "binfmt_flat: don't offset the data start" 2020-08-24 08:49:13 +10:00
binfmt_misc.c binfmt_misc: pass binfmt_misc flags to the interpreter 2021-02-15 18:28:30 +01:00
binfmt_script.c
block_dev.c block-5.12-2021-02-27 2021-02-28 11:23:38 -08:00
buffer.c fs: buffer: use raw page_memcg() on locked page 2021-02-24 13:38:30 -08:00
char_dev.c
compat_binfmt_elf.c get rid of COMPAT_ELF_EXEC_PAGESIZE 2021-01-06 08:42:51 -05:00
coredump.c fs/coredump: use kmap_local_page() 2021-02-26 09:41:05 -08:00
d_path.c fs: fix NULL dereference due to data race in prepend_path() 2020-10-14 14:54:45 -07:00
dax.c mm: provide a saner PTE walking API for modules 2021-02-09 07:05:44 -05:00
dcache.c fs: delete repeated words in comments 2021-02-24 13:38:26 -08:00
direct-io.c block-5.12-2021-02-27 2021-02-28 11:23:38 -08:00
drop_caches.c
eventfd.c eventfd: Export eventfd_ctx_do_read() 2020-11-15 09:49:10 -05:00
eventpoll.c kcmp: Support selection of SYS_kcmp without CHECKPOINT_RESTORE 2021-02-16 09:59:41 +01:00
exec.c fs: delete repeated words in comments 2021-02-24 13:38:26 -08:00
fcntl.c idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
fhandle.c fs: delete repeated words in comments 2021-02-24 13:38:26 -08:00
file.c fs: provide locked helper variant of close_fd_get_file() 2021-02-01 10:02:42 -07:00
file_table.c epoll: take epitem list out of struct file 2020-10-25 20:02:08 -04:00
filesystems.c
fs-writeback.c fs: improve comments for writeback_single_inode() 2021-01-13 17:26:50 +01:00
fs_context.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
fs_parser.c fs_parse: mark fs_param_bad_value() as static 2020-10-13 18:38:27 -07:00
fs_pin.c
fs_struct.c
fs_types.c
fsopen.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
init.c init: handle idmapped mounts 2021-01-24 14:27:19 +01:00
inode.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-02-27 08:07:12 -08:00
internal.h idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
io-wq.c io-wq: kill hashed waitqueue before manager exits 2021-03-05 08:44:09 -07:00
io-wq.h io_uring: move to using create_io_thread() 2021-03-05 08:43:01 -07:00
io_uring.c io_uring: don't restrict issue_flags for io_openat 2021-03-05 09:52:29 -07:00
ioctl.c
kernel_read_file.c fs/kernel_file_read: Add "offset" arg for partial reads 2020-10-05 13:37:04 +02:00
libfs.c idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
locks.c Merge branch 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-12-15 19:29:43 -08:00
mbcache.c
mount.h mount: make {lock,unlock}_mount_hash() static 2021-01-24 14:29:34 +01:00
mpage.c block: Add bio_max_segs 2021-02-26 15:49:51 -07:00
namei.c idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
namespace.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-02-27 08:07:12 -08:00
no-block.c
nsfs.c
open.c idmapped-mounts-v5.12 2021-02-23 13:39:45 -08:00
pipe.c fs: delete repeated words in comments 2021-02-24 13:38:26 -08:00
pnode.c
pnode.h fs/namespace.c: WARN if mnt_count has become negative 2020-12-10 17:33:17 -05:00
posix_acl.c fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
proc_namespace.c fs: introduce MOUNT_ATTR_IDMAP 2021-01-24 14:43:45 +01:00
read_write.c teach sendfile(2) to handle send-to-pipe directly 2021-01-25 23:29:36 -05:00
readdir.c
remap_range.c ioctl: handle idmapped mounts 2021-01-24 14:27:19 +01:00
select.c poll: fix performance regression due to out-of-line __put_user() 2021-01-08 11:06:29 -08:00
seq_file.c fs: fix kernel-doc markups 2021-01-21 14:06:00 -07:00
signalfd.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
splice.c for-5.12/block-2021-02-17 2021-02-21 11:02:48 -08:00
stack.c
stat.c fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
statfs.c s390,alpha: switch to 64-bit ino_t 2021-02-13 17:17:53 +01:00
super.c It has been a relatively quiet cycle in docsland. 2021-02-22 10:57:46 -08:00
sync.c
timerfd.c
userfaultfd.c userfaultfd: use secure anon inodes for userfaultfd 2021-01-14 17:40:57 -05:00
utimes.c utimes: handle idmapped mounts 2021-01-24 14:27:18 +01:00
xattr.c namei: handle idmapped mounts in may_*() helpers 2021-01-24 14:27:17 +01:00