Commit 868f9f2f8e ("vfs: fix copy_file_range() regression in cross-fs
copies") removed fallback to generic_copy_file_range() for cross-fs
cases inside vfs_copy_file_range().
To preserve behavior of nfsd and ksmbd server-side-copy, the fallback to
generic_copy_file_range() was added in nfsd and ksmbd code, but that
call is missing sb_start_write(), fsnotify hooks and more.
Ideally, nfsd and ksmbd would pass a flag to vfs_copy_file_range() that
will take care of the fallback, but that code would be subtle and we got
vfs_copy_file_range() logic wrong too many times already.
Instead, add a flag to explicitly request vfs_copy_file_range() to
perform only generic_copy_file_range() and let nfsd and ksmbd use this
flag only in the fallback path.
This choise keeps the logic changes to minimum in the non-nfsd/ksmbd code
paths to reduce the risk of further regressions.
Fixes: 868f9f2f8e ("vfs: fix copy_file_range() regression in cross-fs copies")
Tested-by: Namjae Jeon <linkinjeon@kernel.org>
Tested-by: Luis Henriques <lhenriques@suse.de>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
passing kmap_local_page() result to __kernel_write() is unsafe -
random ->write_iter() might (and 9p one does) get unhappy when
passed ITER_KVEC with pointer that came from kmap_local_page().
Fix by providing a variant of __kernel_write() that takes an iov_iter
from caller (__kernel_write() becomes a trivial wrapper) and adding
dump_emit_page() that parallels dump_emit(), except that instead of
__kernel_write() it uses __kernel_write_iter() with ITER_BVEC source.
Fixes: 3159ed5779 "fs/coredump: use kmap_local_page()"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
magical no_llseek thing and makes checks consistent. In particular,
ad-hoc "can we do splice via internal pipe" checks got saner (and
somewhat more permissive, which is what Jason had been after, AFAICT)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-work.lseek' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs lseek updates from Al Viro:
"Jason's lseek series.
Saner handling of 'lseek should fail with ESPIPE' - this gets rid of
the magical no_llseek thing and makes checks consistent.
In particular, the ad-hoc "can we do splice via internal pipe" checks
got saner (and somewhat more permissive, which is what Jason had been
after, AFAICT)"
* tag 'pull-work.lseek' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: remove no_llseek
fs: check FMODE_LSEEK to control internal pipe splicing
vfio: do not set FMODE_LSEEK flag
dma-buf: remove useless FMODE_LSEEK flag
fs: do not compare against ->llseek
fs: clear or set FMODE_LSEEK based on llseek function
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Merge tag 'for-5.20/io_uring-buffered-writes-2022-07-29' of git://git.kernel.dk/linux-block
Pull io_uring buffered writes support from Jens Axboe:
"This contains support for buffered writes, specifically for XFS. btrfs
is in progress, will be coming in the next release.
io_uring does support buffered writes on any file type, but since the
buffered write path just always -EAGAIN (or -EOPNOTSUPP) any attempt
to do so if IOCB_NOWAIT is set, any buffered write will effectively be
handled by io-wq offload. This isn't very efficient, and we even have
specific code in io-wq to serialize buffered writes to the same inode
to avoid further inefficiencies with thread offload.
This is particularly sad since most buffered writes don't block, they
simply copy data to a page and dirty it. With this pull request, we
can handle buffered writes a lot more effiently.
If balance_dirty_pages() needs to block, we back off on writes as
indicated.
This improves buffered write support by 2-3x.
Jan Kara helped with the mm bits for this, and Stefan handled the
fs/iomap/xfs/io_uring parts of it"
* tag 'for-5.20/io_uring-buffered-writes-2022-07-29' of git://git.kernel.dk/linux-block:
mm: honor FGP_NOWAIT for page cache page allocation
xfs: Add async buffered write support
xfs: Specify lockmode when calling xfs_ilock_for_iomap()
io_uring: Add tracepoint for short writes
io_uring: fix issue with io_write() not always undoing sb_start_write()
io_uring: Add support for async buffered writes
fs: Add async write file modification handling.
fs: Split off inode_needs_update_time and __file_update_time
fs: add __remove_file_privs() with flags parameter
fs: add a FMODE_BUF_WASYNC flags for f_mode
iomap: Return -EAGAIN from iomap_write_iter()
iomap: Add async buffered write support
iomap: Add flags parameter to iomap_page_create()
mm: Add balance_dirty_pages_ratelimited_flags() function
mm: Move updates of dirty_exceeded into one place
mm: Move starting of background writeback into the main balancing loop
issues or are too minor to warrant backporting
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Merge tag 'mm-hotfixes-stable-2022-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
"Thirteen hotfixes.
Eight are cc:stable and the remainder are for post-5.18 issues or are
too minor to warrant backporting"
* tag 'mm-hotfixes-stable-2022-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
mailmap: update Gao Xiang's email addresses
userfaultfd: provide properly masked address for huge-pages
Revert "ocfs2: mount shared volume without ha stack"
hugetlb: fix memoryleak in hugetlb_mcopy_atomic_pte
fs: sendfile handles O_NONBLOCK of out_fd
ntfs: fix use-after-free in ntfs_ucsncmp()
secretmem: fix unhandled fault in truncate
mm/hugetlb: separate path for hwpoison entry in copy_hugetlb_page_range()
mm: fix missing wake-up event for FSDAX pages
mm: fix page leak with multiple threads mapping the same page
mailmap: update Seth Forshee's email address
tmpfs: fix the issue that the mount and remount results are inconsistent.
mm: kfence: apply kmemleak_ignore_phys on early allocated pool
This introduces the flag FMODE_BUF_WASYNC. If devices support async
buffered writes, this flag can be set. It also modifies the check in
generic_write_checks to take async buffered writes into consideration.
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20220623175157.1715274-8-shr@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that all callers of ->llseek are going through vfs_llseek(), we
don't gain anything by keeping no_llseek around. Nothing actually calls
it and setting ->llseek to no_lseek is completely equivalent to
leaving it NULL.
Longer term (== by the end of merge window) we want to remove all such
intializations. To simplify the merge window this commit does *not*
touch initializers - it only defines no_llseek as NULL (and simplifies
the tests on file opening).
At -rc1 we'll need do a mechanical removal of no_llseek -
git grep -l -w no_llseek | grep -v porting.rst | while read i; do
sed -i '/\<no_llseek\>/d' $i
done
would do it.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Now vfs_llseek() can simply check for FMODE_LSEEK; if it's set,
we know that ->llseek() won't be NULL and if it's not we should
just fail with -ESPIPE.
A couple of other places where we used to check for special
values of ->llseek() (somewhat inconsistently) switched to
checking FMODE_LSEEK.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
A regression has been reported by Nicolas Boichat, found while using the
copy_file_range syscall to copy a tracefs file.
Before commit 5dae222a5f ("vfs: allow copy_file_range to copy across
devices") the kernel would return -EXDEV to userspace when trying to
copy a file across different filesystems. After this commit, the
syscall doesn't fail anymore and instead returns zero (zero bytes
copied), as this file's content is generated on-the-fly and thus reports
a size of zero.
Another regression has been reported by He Zhe - the assertion of
WARN_ON_ONCE(ret == -EOPNOTSUPP) can be triggered from userspace when
copying from a sysfs file whose read operation may return -EOPNOTSUPP.
Since we do not have test coverage for copy_file_range() between any two
types of filesystems, the best way to avoid these sort of issues in the
future is for the kernel to be more picky about filesystems that are
allowed to do copy_file_range().
This patch restores some cross-filesystem copy restrictions that existed
prior to commit 5dae222a5f ("vfs: allow copy_file_range to copy across
devices"), namely, cross-sb copy is not allowed for filesystems that do
not implement ->copy_file_range().
Filesystems that do implement ->copy_file_range() have full control of
the result - if this method returns an error, the error is returned to
the user. Before this change this was only true for fs that did not
implement the ->remap_file_range() operation (i.e. nfsv3).
Filesystems that do not implement ->copy_file_range() still fall-back to
the generic_copy_file_range() implementation when the copy is within the
same sb. This helps the kernel can maintain a more consistent story
about which filesystems support copy_file_range().
nfsd and ksmbd servers are modified to fall-back to the
generic_copy_file_range() implementation in case vfs_copy_file_range()
fails with -EOPNOTSUPP or -EXDEV, which preserves behavior of
server-side-copy.
fall-back to generic_copy_file_range() is not implemented for the smb
operation FSCTL_DUPLICATE_EXTENTS_TO_FILE, which is arguably a correct
change of behavior.
Fixes: 5dae222a5f ("vfs: allow copy_file_range to copy across devices")
Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/
Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/
Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/
Link: https://lore.kernel.org/linux-fsdevel/20210630161320.29006-1-lhenriques@suse.de/
Reported-by: Nicolas Boichat <drinkcat@chromium.org>
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Luis Henriques <lhenriques@suse.de>
Fixes: 64bf5ff58d ("vfs: no fallback for ->copy_file_range")
Link: https://lore.kernel.org/linux-fsdevel/20f17f64-88cb-4e80-07c1-85cb96c83619@windriver.com/
Reported-by: He Zhe <zhe.he@windriver.com>
Tested-by: Namjae Jeon <linkinjeon@kernel.org>
Tested-by: Luis Henriques <lhenriques@suse.de>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull vfs updates from Al Viro:
"Assorted bits and pieces"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
aio: drop needless assignment in aio_read()
clean overflow checks in count_mounts() a bit
seq_file: fix NULL pointer arithmetic warning
uml/x86: use x86 load_unaligned_zeropad()
asm/user.h: killed unused macros
constify struct path argument of finish_automount()/do_add_mount()
fs: Remove FIXME comment in generic_write_checks()
Encoded I/O in Btrfs needs to check a write with a given logical size
without an iov_iter that matches that size (because the iov_iter we have
is for the compressed data). So, factor out the parts of
generic_write_check() that don't need an iov_iter into a new
generic_write_checks_count() function and export that.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
I'm adding btrfs ioctls to read and write compressed data, and rather
than duplicating the checks in rw_verify_area(), let's just export 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>
This patch removes an unnecessary comment that had to do with block special
files from `generic_write_checks()`.
The comment, originally added in Linux v2.4.14.9, was to clarify that we only
set `pos` to the file size when the file was opened with `O_APPEND` if the file
wasn't a block special file. Prior to Linux v2.4, block special files had a
different `write()` function which was unified into a generic `write()` function
in Linux v2.4. This generic `write()` function called `generic_write_checks()`.
For more details, see this earlier conversation:
https://lore.kernel.org/linux-fsdevel/Yc4Czk5A+p5p2Y4W@mit.edu/
Currently, block special devices have their own `write_iter()` function and no
longer share the same `generic_write_checks()`, therefore rendering the comment
irrelevant.
Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Co-authored-by: Xijiao Li <xl2950@columbia.edu>
Co-authored-by: Hans Montero <hjm2133@columbia.edu>
Suggested-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit 3efee0567b4a ("fs: remove mandatory file locking support") removes
some operations in functions rw_verify_area().
As these functions are now simplified, do some syntactic clean-up as
follow-up to the removal as well, which was pointed out by compiler
warnings and static analysis.
No functional change.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
We added CONFIG_MANDATORY_FILE_LOCKING in 2015, and soon after turned it
off in Fedora and RHEL8. Several other distros have followed suit.
I've heard of one problem in all that time: Someone migrated from an
older distro that supported "-o mand" to one that didn't, and the host
had a fstab entry with "mand" in it which broke on reboot. They didn't
actually _use_ mandatory locking so they just removed the mount option
and moved on.
This patch rips out mandatory locking support wholesale from the kernel,
along with the Kconfig option and the Documentation file. It also
changes the mount code to ignore the "mand" mount option instead of
erroring out, and to throw a big, ugly warning.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
- Move the file range remap generic functions out of mm/filemap.c and
fs/read_write.c and into fs/remap_range.c to reduce clutter in the first
two files.
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Merge tag 'vfs-5.10-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull clone/dedupe/remap code refactoring from Darrick Wong:
"Move the generic file range remap (aka reflink and dedupe) functions
out of mm/filemap.c and fs/read_write.c and into fs/remap_range.c to
reduce clutter in the first two files"
* tag 'vfs-5.10-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
vfs: move the generic write and copy checks out of mm
vfs: move the remap range helpers to remap_range.c
vfs: move generic_remap_checks out of mm
Pull initial set_fs() removal from Al Viro:
"Christoph's set_fs base series + fixups"
* 'work.set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: Allow a NULL pos pointer to __kernel_read
fs: Allow a NULL pos pointer to __kernel_write
powerpc: remove address space overrides using set_fs()
powerpc: use non-set_fs based maccess routines
x86: remove address space overrides using set_fs()
x86: make TASK_SIZE_MAX usable from assembly code
x86: move PAGE_OFFSET, TASK_SIZE & friends to page_{32,64}_types.h
lkdtm: remove set_fs-based tests
test_bitmap: remove user bitmap tests
uaccess: add infrastructure for kernel builds with set_fs()
fs: don't allow splice read/write without explicit ops
fs: don't allow kernel reads and writes without iter ops
sysctl: Convert to iter interfaces
proc: add a read_iter method to proc proc_ops
proc: cleanup the compat vs no compat file ops
proc: remove a level of indentation in proc_get_inode
Match the behaviour of new_sync_read() and __kernel_write().
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Linus prefers that callers be allowed to pass in a NULL pointer for ppos
like new_sync_write().
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The generic write check helpers also don't have much to do with the page
cache, so move them to the vfs.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Complete the migration by moving the file remapping helper functions out
of read_write.c and into remap_range.c. This reduces the clutter in the
first file and (eventually) will make it so that we can compile out the
second file if it isn't needed.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Pull compat iovec cleanups from Al Viro:
"Christoph's series around import_iovec() and compat variant thereof"
* 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
security/keys: remove compat_keyctl_instantiate_key_iov
mm: remove compat_process_vm_{readv,writev}
fs: remove compat_sys_vmsplice
fs: remove the compat readv/writev syscalls
fs: remove various compat readv/writev helpers
iov_iter: transparently handle compat iovecs in import_iovec
iov_iter: refactor rw_copy_check_uvector and import_iovec
iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c
compat.h: fix a spelling error in <linux/compat.h>
Now that import_iovec handles compat iovecs, the native readv and writev
syscalls can be used for the compat case as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Now that import_iovec handles compat iovecs as well, all the duplicated
code in the compat readv/writev helpers is not needed. Remove them
and switch the compat syscall handlers to use the native helpers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Use in compat_syscall to import either native or the compat iovecs, and
remove the now superflous compat_import_iovec.
This removes the need for special compat logic in most callers, and
the remaining ones can still be simplified by using __import_iovec
with a bool compat parameter.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
autofs got broken in some configurations by commit 13c164b1a1
("autofs: switch to kernel_write") because there is now an extra LSM
permission check done by security_file_permission() in rw_verify_area().
autofs is one if the few places that really does want the much more
limited __kernel_write(), because the write is an internal kernel one
that shouldn't do any user permission checks (it also doesn't need the
file_start_write/file_end_write logic, since it's just a pipe).
There are a couple of other cases like that - accounting, core dumping,
and splice - but autofs stands out because it can be built as a module.
As a result, we need to export this internal __kernel_write() function
again.
We really don't want any other module to use this, but we don't have a
"EXPORT_SYMBOL_FOR_AUTOFS_ONLY()". But we can mark it GPL-only to at
least approximate that "internal use only" for licensing.
While in this area, make autofs pass in NULL for the file position
pointer, since it's always a pipe, and we now use a NULL file pointer
for streaming file descriptors (see file_ppos() and commit 438ab720c675:
"vfs: pass ppos=NULL to .read()/.write() of FMODE_STREAM files")
This effectively reverts commits 9db9775224 ("fs: unexport
__kernel_write") and 13c164b1a1 ("autofs: switch to kernel_write").
Fixes: 13c164b1a1 ("autofs: switch to kernel_write")
Reported-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This lets the compiler inline it into import_iovec() generating
much better code.
Signed-off-by: David Laight <david.laight@aculab.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
default_file_splice_write is the last piece of generic code that uses
set_fs to make the uaccess routines operate on kernel pointers. It
implements a "fallback loop" for splicing from files that do not actually
provide a proper splice_read method. The usual file systems and other
high bandwidth instances all provide a ->splice_read, so this just removes
support for various device drivers and procfs/debugfs files. If splice
support for any of those turns out to be important it can be added back
by switching them to the iter ops and using generic_file_splice_read.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Don't allow calling ->read or ->write with set_fs as a preparation for
killing off set_fs. All the instances that we use kernel_read/write on
are using the iter ops already.
If a file has both the regular ->read/->write methods and the iter
variants those could have different semantics for messed up enough
drivers. Also fails the kernel access to them in that case.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There is no good reason to mess with file descriptors from in-kernel
code, switch the initrd loading to struct file based read and writes
instead.
Also Pass an explicit offset instead of ->f_pos, and to make that easier,
use file scope file structs and offsets everywhere except for
identify_ramdisk_image instead of the current strange mix.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Consolidate the two in-kernel read helpers to make upcoming changes
easier. The only difference are the missing call to rw_verify_area
in kernel_read, and an access_ok check that doesn't make sense for
kernel buffers to start with.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Consolidate the two in-kernel write helpers to make upcoming changes
easier. The only difference are the missing call to rw_verify_area
in kernel_write, and an access_ok check that doesn't make sense for
kernel buffers to start with.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Add a WARN_ON_ONCE if the file isn't actually open for write. This
matches the check done in vfs_write, but actually warn warns as a
kernel user calling write on a file not opened for writing is a pretty
obvious programming error.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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Merge tag 'ovl-update-5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs update from Miklos Szeredi:
- Try to preserve holes in sparse files when copying up, thus saving
disk space and improving performance.
- Fix a performance regression introduced in v4.19 by preserving
asynchronicity of IO when fowarding to underlying layers. Add VFS
helpers to submit async iocbs.
- Fix a regression in lseek(2) introduced in v4.19 that breaks >2G
seeks on 32bit kernels.
- Fix a corner case where st_ino/st_dev was not preserved across copy
up.
- Miscellaneous fixes and cleanups.
* tag 'ovl-update-5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
ovl: fix lseek overflow on 32bit
ovl: add splice file read write helper
ovl: implement async IO routines
vfs: add vfs_iocb_iter_[read|write] helper functions
ovl: layer is const
ovl: fix corner case of non-constant st_dev;st_ino
ovl: fix corner case of conflicting lower layer uuid
ovl: generalize the lower_fs[] array
ovl: simplify ovl_same_sb() helper
ovl: generalize the lower_layers[] array
ovl: improving copy-up efficiency for big sparse file
ovl: use ovl_inode_lock in ovl_llseek()
ovl: use pr_fmt auto generate prefix
ovl: fix wrong WARN_ON() in ovl_cache_update_ino()
This doesn't cause any behavior changes and will be used by overlay async
IO implementation.
Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
We always round down, to a multiple of the filesystem's block size, the
length to deduplicate at generic_remap_check_len(). However this is only
needed if an attempt to deduplicate the last block into the middle of the
destination file is requested, since that leads into a corruption if the
length of the source file is not block size aligned. When an attempt to
deduplicate the last block into the end of the destination file is
requested, we should allow it because it is safe to do it - there's no
stale data exposure and we are prepared to compare the data ranges for
a length not aligned to the block (or page) size - in fact we even do
the data compare before adjusting the deduplication length.
After btrfs was updated to use the generic helpers from VFS (by commit
34a28e3d77 ("Btrfs: use generic_remap_file_range_prep() for cloning
and deduplication")) we started to have user reports of deduplication
not reflinking the last block anymore, and whence users getting lower
deduplication scores. The main use case is deduplication of entire
files that have a size not aligned to the block size of the filesystem.
We already allow cloning the last block to the end (and beyond) of the
destination file, so allow for deduplication as well.
Link: https://lore.kernel.org/linux-btrfs/2019-1576167349.500456@svIo.N5dq.dFFD/
CC: stable@vger.kernel.org # 5.1+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When dedupe wants to use the page cache to compare parts of two files
for dedupe, we must be very careful to handle locking correctly. The
current code doesn't do this. It must lock and unlock the page only
once if the two pages are the same, since the overlapping range check
doesn't catch this when blocksize < pagesize. If the pages are distinct
but from the same file, we must observe page locking order and lock them
in order of increasing offset to avoid clashing with writeback locking.
Fixes: 876bec6f9b ("vfs: refactor clone/dedupe_file_range common functions")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Bill O'Donnell <billodo@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
We want to enable cross-filesystem copy_file_range functionality
where possible, so push the "same superblock only" checks down to
the individual filesystem callouts so they can make their own
decisions about cross-superblock copy offload and fallack to
generic_copy_file_range() for cross-superblock copy.
[Amir] We do not call ->remap_file_range() in case the files are not
on the same sb and do not call ->copy_file_range() in case the files
do not belong to the same filesystem driver.
This changes behavior of the copy_file_range(2) syscall, which will
now allow cross filesystem in-kernel copy. CIFS already supports
cross-superblock copy, between two shares to the same server. This
functionality will now be available via the copy_file_range(2) syscall.
Cc: Steve French <stfrench@microsoft.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
The combination of file_remove_privs() and file_update_mtime() is
quite common in filesystem ->write_iter() methods.
Modelled after the helper file_accessed(), introduce file_modified()
and use it from generic_remap_file_range_prep().
Note that the order of calling file_remove_privs() before
file_update_mtime() in the helper was matched to the more common order by
filesystems and not the current order in generic_remap_file_range_prep().
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Like the clone and dedupe interfaces we've recently fixed, the
copy_file_range() implementation is missing basic sanity, limits and
boundary condition tests on the parameters that are passed to it
from userspace. Create a new "generic_copy_file_checks()" function
modelled on the generic_remap_checks() function to provide this
missing functionality.
[Amir] Shorten copy length instead of checking pos_in limits
because input file size already abides by the limits.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Amir Goldstein