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Merge tag 'for-6.13-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few more fixes. Apart from the one liners and updated bio splitting
error handling there's a fix for subvolume mount with different flags.
This was known and fixed for some time but I've delayed it to give it
more testing.
- fix unbalanced locking when swapfile activation fails when the
subvolume gets deleted in the meantime
- add btrfs error handling after bio_split() calls that got error
handling recently
- during unmount, flush delalloc workers at the right time before the
cleaner thread is shut down
- fix regression in buffered write folio conversion, explicitly wait
for writeback as FGP_STABLE flag is currently a no-op on btrfs
- handle race in subvolume mount with different flags, the conversion
to the new mount API did not handle the case where multiple
subvolumes get mounted in parallel, which is a distro use case"
* tag 'for-6.13-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: flush delalloc workers queue before stopping cleaner kthread during unmount
btrfs: handle bio_split() errors
btrfs: properly wait for writeback before buffered write
btrfs: fix missing snapshot drew unlock when root is dead during swap activation
btrfs: fix mount failure due to remount races
[BUG]
Before commit e820dbeb6a ("btrfs: convert btrfs_buffered_write() to
use folios"), function prepare_one_folio() will always wait for folio
writeback to finish before returning the folio.
However commit e820dbeb6a ("btrfs: convert btrfs_buffered_write() to
use folios") changed to use FGP_STABLE to do the writeback wait, but
FGP_STABLE is calling folio_wait_stable(), which only calls
folio_wait_writeback() if the address space has AS_STABLE_WRITES, which
is not set for btrfs inodes.
This means we will not wait for the folio writeback at all.
[CAUSE]
The cause is FGP_STABLE is not waiting for writeback unconditionally, but
only for address spaces with AS_STABLE_WRITES, normally such flag is set
when the super block has SB_I_STABLE_WRITES flag.
Such super block flag is set when the block device has hardware digest
support or has internal checksum requirement.
I'd argue btrfs should set such super block due to its default data
checksum behavior, but it is not set yet, so this means FGP_STABLE flag
will have no effect at all.
(For NODATASUM inodes, we can skip the waiting in theory but that should
be an optimization in the future.)
This can lead to data checksum mismatch, as we can modify the folio
while it's still under writeback, this will make the contents differ
from the contents at submission and checksum calculation.
[FIX]
Instead of fully relying on FGP_STABLE, manually do the folio writeback
waiting, until we set the address space or super flag.
Fixes: e820dbeb6a ("btrfs: convert btrfs_buffered_write() to use folios")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-6.13-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"Changes outside of btrfs: add io_uring command flag to track a dying
task (the rest will go via the block git tree).
User visible changes:
- wire encoded read (ioctl) to io_uring commands, this can be used on
itself, in the future this will allow 'send' to be asynchronous. As
a consequence, the encoded read ioctl can also work in non-blocking
mode
- new ioctl to wait for cleaned subvolumes, no need to use the
generic and root-only SEARCH_TREE ioctl, will be used by "btrfs
subvol sync"
- recognize different paths/symlinks for the same devices and don't
report them during rescanning, this can be observed with LVM or DM
- seeding device use case change, the sprout device (the one
capturing new writes) will not clear the read-only status of the
super block; this prevents accumulating space from deleted
snapshots
Performance improvements:
- reduce lock contention when traversing extent buffers
- reduce extent tree lock contention when searching for inline
backref
- switch from rb-trees to xarray for delayed ref tracking,
improvements due to better cache locality, branching factors and
more compact data structures
- enable extent map shrinker again (prevent memory exhaustion under
some types of IO load), reworked to run in a single worker thread
(there used to be problems causing long stalls under memory
pressure)
Core changes:
- raid-stripe-tree feature updates:
- make device replace and scrub work
- implement partial deletion of stripe extents
- new selftests
- split the config option BTRFS_DEBUG and add EXPERIMENTAL for
features that are experimental or with known problems so we don't
misuse debugging config for that
- subpage mode updates (sector < page):
- update compression implementations
- update writepage, writeback
- continued folio API conversions:
- buffered writes
- make buffered write copy one page at a time, preparatory work for
future integration with large folios, may cause performance drop
- proper locking of root item regarding starting send
- error handling improvements
- code cleanups and refactoring:
- dead code removal
- unused parameter reduction
- lockdep assertions"
* tag 'for-6.13-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (119 commits)
btrfs: send: check for read-only send root under critical section
btrfs: send: check for dead send root under critical section
btrfs: remove check for NULL fs_info at btrfs_folio_end_lock_bitmap()
btrfs: fix warning on PTR_ERR() against NULL device at btrfs_control_ioctl()
btrfs: fix a typo in btrfs_use_zone_append
btrfs: avoid superfluous calls to free_extent_map() in btrfs_encoded_read()
btrfs: simplify logic to decrement snapshot counter at btrfs_mksnapshot()
btrfs: remove hole from struct btrfs_delayed_node
btrfs: update stale comment for struct btrfs_delayed_ref_node::add_list
btrfs: add new ioctl to wait for cleaned subvolumes
btrfs: simplify range tracking in cow_file_range()
btrfs: remove conditional path allocation in btrfs_read_locked_inode()
btrfs: push cleanup into btrfs_read_locked_inode()
io_uring/cmd: let cmds to know about dying task
btrfs: add struct io_btrfs_cmd as type for io_uring_cmd_to_pdu()
btrfs: add io_uring command for encoded reads (ENCODED_READ ioctl)
btrfs: move priv off stack in btrfs_encoded_read_regular_fill_pages()
btrfs: don't sleep in btrfs_encoded_read() if IOCB_NOWAIT is set
btrfs: change btrfs_encoded_read() so that reading of extent is done by caller
btrfs: remove pointless iocb::ki_pos addition in btrfs_encoded_read()
...
Add an io_uring command for encoded reads, using the same interface as
the existing BTRFS_IOC_ENCODED_READ ioctl.
btrfs_uring_encoded_read() is an io_uring version of
btrfs_ioctl_encoded_read(), which validates the user input and calls
btrfs_encoded_read() to read the appropriate metadata. If we determine
that we need to read an extent from disk, we call
btrfs_encoded_read_regular_fill_pages() through
btrfs_uring_read_extent() to prepare the bio.
The existing btrfs_encoded_read_regular_fill_pages() is changed so that
if it is passed a valid uring_ctx, rather than waking up any waiting
threads it calls btrfs_uring_read_extent_endio(). This in turn copies
the read data back to userspace, and calls io_uring_cmd_done() to
complete the io_uring command.
Because we're potentially doing a non-blocking read,
btrfs_uring_read_extent() doesn't clean up after itself if it returns
-EIOCBQUEUED. Instead, it allocates a priv struct, populates the fields
there that we will need to unlock the inode and free our allocations,
and defers this to the btrfs_uring_read_finished() that gets called when
the bio completes.
Signed-off-by: Mark Harmstone <maharmstone@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The buffered write path is still heavily utilizing the page interface.
Since we have converted it to do a page-by-page copying, it's much easier
to convert all involved functions to folio interface, this involves:
- btrfs_copy_from_user()
- btrfs_drop_folio()
- prepare_uptodate_page()
- prepare_one_page()
- lock_and_cleanup_extent_if_need()
- btrfs_dirty_page()
All function are changed to accept a folio parameter, and if the word
"page" is in the function name, change that to "folio" too.
The function btrfs_dirty_page() is exported for v1 space cache, convert
v1 cache call site to convert its page to folio for the new interface.
And there is a small enhancement for prepare_one_folio(), instead of
manually waiting for the page writeback, let __filemap_get_folio() to
handle that by using FGP_WRITEBEGIN, which implies
(FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE).
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently the btrfs_buffered_write() is preparing multiple page a time,
allowing a better performance.
But the current trend is to support larger folio as an optimization,
instead of implementing own multi-page optimization.
This is inspired by generic_perform_write(), which is copying one folio
a time.
Such change will prepare us to migrate to implement the write_begin()
and write_end() callbacks, and make every involved function a little
easier.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The parameter 'from' has never been used since commit b8d8e1fd57
("btrfs: introduce btrfs_write_check()"), this is for buffered write.
Direct io write needs it so it was probably an interface thing, but we
can drop it.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently inside prepare_pages(), we handle the leading and tailing page
differently, and skip the middle pages (if any). This is to avoid
reading pages which are fully covered by the dirty range.
Refactor the code by moving all checks (alignment check, range check,
force read check) into prepare_uptodate_page().
So that prepare_pages() only needs to iterate all the pages
unconditionally.
And since we're here, also update prepare_uptodate_page() to use
folio API other than the old page API.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Inside btrfs_buffered_write(), we have a local variable @dirty_pages,
recording the number of pages we dirtied in the current iteration.
However we do not really need that variable, since it can be calculated
from @pos and @copied.
In fact there is already a problem inside the short copy path, where we
use @dirty_pages to calculate the range we need to release.
But that usage assumes sectorsize == PAGE_SIZE, which is no longer true.
Instead of keeping @dirty_pages and cause incorrect usage, just
calculate the number of dirtied pages inside btrfs_dirty_pages().
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Jeff Layton <jlayton@kernel.org> says:
The VFS has always used coarse-grained timestamps when updating the
ctime and mtime after a change. This has the benefit of allowing
filesystems to optimize away a lot metadata updates, down to around 1
per jiffy, even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting via
NFSv3, which relies on timestamps to validate caches. A lot of changes
can happen in a jiffy, so timestamps aren't sufficient to help the
client decide when to invalidate the cache. Even with NFSv4, a lot of
exported filesystems don't properly support a change attribute and are
subject to the same problems with timestamp granularity. Other
applications have similar issues with timestamps (e.g backup
applications).
If we were to always use fine-grained timestamps, that would improve the
situation, but that becomes rather expensive, as the underlying
filesystem would have to log a lot more metadata updates.
What we need is a way to only use fine-grained timestamps when they are
being actively queried. Use the (unused) top bit in inode->i_ctime_nsec
as a flag that indicates whether the current timestamps have been
queried via stat() or the like. When it's set, we allow the kernel to
use a fine-grained timestamp iff it's necessary to make the ctime show
a different value.
This solves the problem of being able to distinguish the timestamp
between updates, but introduces a new problem: it's now possible for a
file being changed to get a fine-grained timestamp. A file that is
altered just a bit later can then get a coarse-grained one that appears
older than the earlier fine-grained time. This violates timestamp
ordering guarantees.
To remedy this, keep a global monotonic atomic64_t value that acts as a
timestamp floor. When we go to stamp a file, we first get the latter of
the current floor value and the current coarse-grained time. If the
inode ctime hasn't been queried then we just attempt to stamp it with
that value.
If it has been queried, then first see whether the current coarse time
is later than the existing ctime. If it is, then we accept that value.
If it isn't, then we get a fine-grained time and try to swap that into
the global floor. Whether that succeeds or fails, we take the resulting
floor time, convert it to realtime and try to swap that into the ctime.
We take the result of the ctime swap whether it succeeds or fails, since
either is just as valid.
Filesystems can opt into this by setting the FS_MGTIME fstype flag.
Others should be unaffected (other than being subject to the same floor
value as multigrain filesystems).
* patches from https://lore.kernel.org/r/20241002-mgtime-v10-0-d1c4717f5284@kernel.org:
tmpfs: add support for multigrain timestamps
btrfs: convert to multigrain timestamps
ext4: switch to multigrain timestamps
xfs: switch to multigrain timestamps
Documentation: add a new file documenting multigrain timestamps
fs: add percpu counters for significant multigrain timestamp events
fs: tracepoints around multigrain timestamp events
fs: handle delegated timestamps in setattr_copy_mgtime
fs: have setattr_copy handle multigrain timestamps appropriately
fs: add infrastructure for multigrain timestamps
Link: https://lore.kernel.org/r/20241002-mgtime-v10-0-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Enable multigrain timestamps, which should ensure that there is an
apparent change to the timestamp whenever it has been written after
being actively observed via getattr.
Beyond enabling the FS_MGTIME flag, this patch eliminates
update_time_for_write, which goes to great pains to avoid in-memory
stores. Just have it overwrite the timestamps unconditionally.
Note that this also drops the IS_I_VERSION check and unconditionally
bumps the change attribute, since SB_I_VERSION is always set on btrfs.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241002-mgtime-v10-11-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
When doing concurrent lseek(2) system calls against the same file
descriptor, using multiple threads belonging to the same process, we have
a short time window where a race happens and can result in a memory leak.
The race happens like this:
1) A program opens a file descriptor for a file and then spawns two
threads (with the pthreads library for example), lets call them
task A and task B;
2) Task A calls lseek with SEEK_DATA or SEEK_HOLE and ends up at
file.c:find_desired_extent() while holding a read lock on the inode;
3) At the start of find_desired_extent(), it extracts the file's
private_data pointer into a local variable named 'private', which has
a value of NULL;
4) Task B also calls lseek with SEEK_DATA or SEEK_HOLE, locks the inode
in shared mode and enters file.c:find_desired_extent(), where it also
extracts file->private_data into its local variable 'private', which
has a NULL value;
5) Because it saw a NULL file private, task A allocates a private
structure and assigns to the file structure;
6) Task B also saw a NULL file private so it also allocates its own file
private and then assigns it to the same file structure, since both
tasks are using the same file descriptor.
At this point we leak the private structure allocated by task A.
Besides the memory leak, there's also the detail that both tasks end up
using the same cached state record in the private structure (struct
btrfs_file_private::llseek_cached_state), which can result in a
use-after-free problem since one task can free it while the other is
still using it (only one task took a reference count on it). Also, sharing
the cached state is not a good idea since it could result in incorrect
results in the future - right now it should not be a problem because it
end ups being used only in extent-io-tree.c:count_range_bits() where we do
range validation before using the cached state.
Fix this by protecting the private assignment and check of a file while
holding the inode's spinlock and keep track of the task that allocated
the private, so that it's used only by that task in order to prevent
user-after-free issues with the cached state record as well as potentially
using it incorrectly in the future.
Fixes: 3c32c7212f ("btrfs: use cached state when looking for delalloc ranges with lseek")
CC: stable@vger.kernel.org # 6.6+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have a few places that check if we have the inode locked by doing:
ASSERT(inode_is_locked(vfs_inode));
This actually proved to be useful several times as if assertions are
enabled (and by default they are in many distros) it immediately triggers
a crash which is impossible for users to miss.
However that doesn't check if the lock is held by the calling task, so
the check passes if some other task locked the inode.
Using one of the lockdep functions to check the lock is held, like
lockdep_assert_held() for example, does check that the calling task
holds the lock, and if that's not the case it produces a warning and
stack trace in dmesg. However, despite the misleading "assert" in the
name of the lockdep helpers, it does not trigger a crash/BUG_ON(), just
a warning and splat in dmesg, which is easy to get unnoticed by users
who may have lockdep enabled.
So add a helper that does the ASSERT() and calls lockdep_assert_held()
immediately after and use it every where we check the inode is locked.
Like this if the lock is held by some other task we get the warning
in dmesg which is caught by fstests, very helpful during development,
and may also be occassionaly noticed by users with lockdep enabled.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We already have a folio that we're using in btrfs_page_mkwrite, update
the rest of the function to use folio everywhere else. This will make
it easier on Willy when he drops page->index.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we have 2 threads that are using the same file descriptor and one of
them is doing direct IO writes while the other is doing fsync, we have a
race where we can end up either:
1) Attempt a fsync without holding the inode's lock, triggering an
assertion failures when assertions are enabled;
2) Do an invalid memory access from the fsync task because the file private
points to memory allocated on stack by the direct IO task and it may be
used by the fsync task after the stack was destroyed.
The race happens like this:
1) A user space program opens a file descriptor with O_DIRECT;
2) The program spawns 2 threads using libpthread for example;
3) One of the threads uses the file descriptor to do direct IO writes,
while the other calls fsync using the same file descriptor.
4) Call task A the thread doing direct IO writes and task B the thread
doing fsyncs;
5) Task A does a direct IO write, and at btrfs_direct_write() sets the
file's private to an on stack allocated private with the member
'fsync_skip_inode_lock' set to true;
6) Task B enters btrfs_sync_file() and sees that there's a private
structure associated to the file which has 'fsync_skip_inode_lock' set
to true, so it skips locking the inode's VFS lock;
7) Task A completes the direct IO write, and resets the file's private to
NULL since it had no prior private and our private was stack allocated.
Then it unlocks the inode's VFS lock;
8) Task B enters btrfs_get_ordered_extents_for_logging(), then the
assertion that checks the inode's VFS lock is held fails, since task B
never locked it and task A has already unlocked it.
The stack trace produced is the following:
assertion failed: inode_is_locked(&inode->vfs_inode), in fs/btrfs/ordered-data.c:983
------------[ cut here ]------------
kernel BUG at fs/btrfs/ordered-data.c:983!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP PTI
CPU: 9 PID: 5072 Comm: worker Tainted: G U OE 6.10.5-1-default #1 openSUSE Tumbleweed 69f48d427608e1c09e60ea24c6c55e2ca1b049e8
Hardware name: Acer Predator PH315-52/Covini_CFS, BIOS V1.12 07/28/2020
RIP: 0010:btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs]
Code: 50 d6 86 c0 e8 (...)
RSP: 0018:ffff9e4a03dcfc78 EFLAGS: 00010246
RAX: 0000000000000054 RBX: ffff9078a9868e98 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff907dce4a7800 RDI: ffff907dce4a7800
RBP: ffff907805518800 R08: 0000000000000000 R09: ffff9e4a03dcfb38
R10: ffff9e4a03dcfb30 R11: 0000000000000003 R12: ffff907684ae7800
R13: 0000000000000001 R14: ffff90774646b600 R15: 0000000000000000
FS: 00007f04b96006c0(0000) GS:ffff907dce480000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f32acbfc000 CR3: 00000001fd4fa005 CR4: 00000000003726f0
Call Trace:
<TASK>
? __die_body.cold+0x14/0x24
? die+0x2e/0x50
? do_trap+0xca/0x110
? do_error_trap+0x6a/0x90
? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]
? exc_invalid_op+0x50/0x70
? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]
? asm_exc_invalid_op+0x1a/0x20
? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]
? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]
btrfs_sync_file+0x21a/0x4d0 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]
? __seccomp_filter+0x31d/0x4f0
__x64_sys_fdatasync+0x4f/0x90
do_syscall_64+0x82/0x160
? do_futex+0xcb/0x190
? __x64_sys_futex+0x10e/0x1d0
? switch_fpu_return+0x4f/0xd0
? syscall_exit_to_user_mode+0x72/0x220
? do_syscall_64+0x8e/0x160
? syscall_exit_to_user_mode+0x72/0x220
? do_syscall_64+0x8e/0x160
? syscall_exit_to_user_mode+0x72/0x220
? do_syscall_64+0x8e/0x160
? syscall_exit_to_user_mode+0x72/0x220
? do_syscall_64+0x8e/0x160
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Another problem here is if task B grabs the private pointer and then uses
it after task A has finished, since the private was allocated in the stack
of task A, it results in some invalid memory access with a hard to predict
result.
This issue, triggering the assertion, was observed with QEMU workloads by
two users in the Link tags below.
Fix this by not relying on a file's private to pass information to fsync
that it should skip locking the inode and instead pass this information
through a special value stored in current->journal_info. This is safe
because in the relevant section of the direct IO write path we are not
holding a transaction handle, so current->journal_info is NULL.
The following C program triggers the issue:
$ cat repro.c
/* Get the O_DIRECT definition. */
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
static int fd;
static ssize_t do_write(int fd, const void *buf, size_t count, off_t offset)
{
while (count > 0) {
ssize_t ret;
ret = pwrite(fd, buf, count, offset);
if (ret < 0) {
if (errno == EINTR)
continue;
return ret;
}
count -= ret;
buf += ret;
}
return 0;
}
static void *fsync_loop(void *arg)
{
while (1) {
int ret;
ret = fsync(fd);
if (ret != 0) {
perror("Fsync failed");
exit(6);
}
}
}
int main(int argc, char *argv[])
{
long pagesize;
void *write_buf;
pthread_t fsyncer;
int ret;
if (argc != 2) {
fprintf(stderr, "Use: %s <file path>\n", argv[0]);
return 1;
}
fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC | O_DIRECT, 0666);
if (fd == -1) {
perror("Failed to open/create file");
return 1;
}
pagesize = sysconf(_SC_PAGE_SIZE);
if (pagesize == -1) {
perror("Failed to get page size");
return 2;
}
ret = posix_memalign(&write_buf, pagesize, pagesize);
if (ret) {
perror("Failed to allocate buffer");
return 3;
}
ret = pthread_create(&fsyncer, NULL, fsync_loop, NULL);
if (ret != 0) {
fprintf(stderr, "Failed to create writer thread: %d\n", ret);
return 4;
}
while (1) {
ret = do_write(fd, write_buf, pagesize, 0);
if (ret != 0) {
perror("Write failed");
exit(5);
}
}
return 0;
}
$ mkfs.btrfs -f /dev/sdi
$ mount /dev/sdi /mnt/sdi
$ timeout 10 ./repro /mnt/sdi/foo
Usually the race is triggered within less than 1 second. A test case for
fstests will follow soon.
Reported-by: Paulo Dias <paulo.miguel.dias@gmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219187
Reported-by: Andreas Jahn <jahn-andi@web.de>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219199
Reported-by: syzbot+4704b3cc972bd76024f1@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/00000000000044ff540620d7dee2@google.com/
Fixes: 939b656bc8 ("btrfs: fix corruption after buffer fault in during direct IO append write")
CC: stable@vger.kernel.org # 5.15+
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>
If we do a direct IO sync write, at btrfs_sync_file(), and we need to skip
inode logging or we get an error starting a transaction or an error when
flushing delalloc, we end up unlocking the inode when we shouldn't under
the 'out_release_extents' label, and then unlock it again at
btrfs_direct_write().
Fix that by checking if we have to skip inode unlocking under that label.
Reported-by: syzbot+7dbbb74af6291b5a5a8b@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/000000000000dfd631061eaeb4bc@google.com/
Fixes: 939b656bc8 ("btrfs: fix corruption after buffer fault in during direct IO append write")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
During an append (O_APPEND write flag) direct IO write if the input buffer
was not previously faulted in, we can corrupt the file in a way that the
final size is unexpected and it includes an unexpected hole.
The problem happens like this:
1) We have an empty file, with size 0, for example;
2) We do an O_APPEND direct IO with a length of 4096 bytes and the input
buffer is not currently faulted in;
3) We enter btrfs_direct_write(), lock the inode and call
generic_write_checks(), which calls generic_write_checks_count(), and
that function sets the iocb position to 0 with the following code:
if (iocb->ki_flags & IOCB_APPEND)
iocb->ki_pos = i_size_read(inode);
4) We call btrfs_dio_write() and enter into iomap, which will end up
calling btrfs_dio_iomap_begin() and that calls
btrfs_get_blocks_direct_write(), where we update the i_size of the
inode to 4096 bytes;
5) After btrfs_dio_iomap_begin() returns, iomap will attempt to access
the page of the write input buffer (at iomap_dio_bio_iter(), with a
call to bio_iov_iter_get_pages()) and fail with -EFAULT, which gets
returned to btrfs at btrfs_direct_write() via btrfs_dio_write();
6) At btrfs_direct_write() we get the -EFAULT error, unlock the inode,
fault in the write buffer and then goto to the label 'relock';
7) We lock again the inode, do all the necessary checks again and call
again generic_write_checks(), which calls generic_write_checks_count()
again, and there we set the iocb's position to 4K, which is the current
i_size of the inode, with the following code pointed above:
if (iocb->ki_flags & IOCB_APPEND)
iocb->ki_pos = i_size_read(inode);
8) Then we go again to btrfs_dio_write() and enter iomap and the write
succeeds, but it wrote to the file range [4K, 8K), leaving a hole in
the [0, 4K) range and an i_size of 8K, which goes against the
expectations of having the data written to the range [0, 4K) and get an
i_size of 4K.
Fix this by not unlocking the inode before faulting in the input buffer,
in case we get -EFAULT or an incomplete write, and not jumping to the
'relock' label after faulting in the buffer - instead jump to a location
immediately before calling iomap, skipping all the write checks and
relocking. This solves this problem and it's fine even in case the input
buffer is memory mapped to the same file range, since only holding the
range locked in the inode's io tree can cause a deadlock, it's safe to
keep the inode lock (VFS lock), as was fixed and described in commit
51bd9563b6 ("btrfs: fix deadlock due to page faults during direct IO
reads and writes").
A sample reproducer provided by a reporter is the following:
$ cat test.c
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <fcntl.h>
#include <stdio.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
if (argc < 2) {
fprintf(stderr, "Usage: %s <test file>\n", argv[0]);
return 1;
}
int fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC | O_DIRECT |
O_APPEND, 0644);
if (fd < 0) {
perror("creating test file");
return 1;
}
char *buf = mmap(NULL, 4096, PROT_READ,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
ssize_t ret = write(fd, buf, 4096);
if (ret < 0) {
perror("pwritev2");
return 1;
}
struct stat stbuf;
ret = fstat(fd, &stbuf);
if (ret < 0) {
perror("stat");
return 1;
}
printf("size: %llu\n", (unsigned long long)stbuf.st_size);
return stbuf.st_size == 4096 ? 0 : 1;
}
A test case for fstests will be sent soon.
Reported-by: Hanna Czenczek <hreitz@redhat.com>
Link: https://lore.kernel.org/linux-btrfs/0b841d46-12fe-4e64-9abb-871d8d0de271@redhat.com/
Fixes: 8184620ae2 ("btrfs: fix lost file sync on direct IO write with nowait and dsync iocb")
CC: stable@vger.kernel.org # 6.1+
Tested-by: Hanna Czenczek <hreitz@redhat.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The direct IO code is over a thousand lines and it's currently spread
between file.c and inode.c, which makes it not easy to locate some parts
of it sometimes. Also inode.c is about 11 thousand lines and file.c about
4 thousand lines, both too big. So move all the direct IO code into a
dedicated file, so that it's easy to locate all its code and reduce the
sizes of inode.c and file.c.
This is a pure move of code without any other changes except export a
a couple functions from inode.c (get_extent_allocation_hint() and
create_io_em()) because they are used in inode.c and the new direct-io.c
file, and a couple functions from file.c (btrfs_buffered_write() and
btrfs_write_check()) because they are used both in file.c and in the new
direct-io.c file.
Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The following functions and structures can be simplified using the
btrfs_file_extent structure:
- can_nocow_extent()
No need to return ram_bytes/orig_block_len through the parameter list,
the @file_extent parameter contains all the needed info.
- can_nocow_file_extent_args
The following members are no longer needed:
* disk_bytenr
This one is confusing as it's not really the
btrfs_file_extent_item::disk_bytenr, but where the IO would be,
thus it's file_extent::disk_bytenr + file_extent::offset now.
* num_bytes
Now file_extent::num_bytes.
* extent_offset
Now file_extent::offset.
* disk_num_bytes
Now file_extent::disk_num_bytes.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@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>
The member extent_map::block_start can be calculated from
extent_map::disk_bytenr + extent_map::offset for regular extents.
And otherwise just extent_map::disk_bytenr.
And this is already validated by the validate_extent_map(). Now we can
remove the member.
However there is a special case in btrfs_create_dio_extent() where we
for NOCOW/PREALLOC ordered extents cannot directly use the resulting
btrfs_file_extent, as btrfs_split_ordered_extent() cannot handle them
yet.
So for that call site, we pass file_extent->disk_bytenr +
file_extent->num_bytes as disk_bytenr for the ordered extent, and 0 for
offset.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@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>
The extent_map::block_len is either extent_map::len (non-compressed
extent) or extent_map::disk_num_bytes (compressed extent).
Since we already have sanity checks to do the cross-checks between the
new and old members, we can drop the old extent_map::block_len now.
For most call sites, they can manually select extent_map::len or
extent_map::disk_num_bytes, since most if not all of them have checked
if the extent is compressed.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@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>
Since we have extent_map::offset, the old extent_map::orig_start is just
extent_map::start - extent_map::offset for non-hole/inline extents.
And since the new extent_map::offset is already verified by
validate_extent_map() while the old orig_start is not, let's just remove
the old member from all call sites.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@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>
Introduce two new members for extent_map:
- disk_bytenr
- offset
Both are matching the members with the same name inside
btrfs_file_extent_items.
For now this patch only touches those members when:
- Reading btrfs_file_extent_items from disk
- Inserting new holes
- Merging two extent maps
With the new disk_bytenr and disk_num_bytes, doing merging would be a
little more complex, as we have 3 different cases:
* Both extent maps are referring to the same data extents
|<----- data extent A ----->|
|<- em 1 ->|<- em 2 ->|
* Both extent maps are referring to different data extents
|<-- data extent A -->|<-- data extent B -->|
|<- em 1 ->|<- em 2 ->|
* One of the extent maps is referring to a merged and larger data
extent that covers both extent maps
This is not really valid case other than some selftests.
So this test case would be removed.
A new helper merge_ondisk_extents() is introduced to handle the above
valid cases.
To properly assign values for those new members, a new btrfs_file_extent
parameter is introduced to all the involved call sites.
- For NOCOW writes the btrfs_file_extent would be exposed from
can_nocow_file_extent().
- For other writes, the members can be easily calculated
As most of them have 0 offset and utilizing the whole on-disk data
extent.
The exception is encoded write, but thankfully that interface provided
offset directly and all other needed info.
For now, both the old members (block_start/block_len/orig_start) are
co-existing with the new members (disk_bytenr/offset), meanwhile all the
critical code is still using the old members only.
The cleanup will happen later after all the old and new members are
properly validated.
There would be some re-ordering for the assignment of the extent_map
members, now we follow the new ordering:
- start and len
Or file_pos and num_bytes for other structures.
- disk_bytenr and disk_num_bytes
- offset and ram_bytes
- compression
So expect some seemingly unrelated line movement.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@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>
Currently function can_nocow_extent() only returns members needed for
extent_map.
However since we will soon change the extent_map structure to be more
like btrfs_file_extent_item, we want to expose the expected file extent
caused by the NOCOW write for future usage.
This introduces a new structure, btrfs_file_extent, to be a more
memory access friendly representation of btrfs_file_extent_item.
And use that structure to expose the expected file extent caused by the
NOCOW write.
For now there is no user of the new structure yet.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@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>
This would make it very obvious that the member just matches
btrfs_file_extent_item::disk_num_bytes.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@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>
Instead of using a VFS inode local pointer and then doing many BTRFS_I()
calls inside btrfs_sync_file(), use a btrfs_inode pointer instead. This
makes everything a bit easier to read and less confusing, allowing to
make some statements shorter.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of passing a (VFS) inode pointer argument, pass a btrfs_inode
instead, as this is generally what we do for internal APIs, making it
more consistent with most of the code base. This will later allow to
help to remove a lot of BTRFS_I() calls in btrfs_sync_file().
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of passing a (VFS) inode pointer argument, pass a btrfs_inode
instead, as this is generally what we do for internal APIs, making it
more consistent with most of the code base. This will later allow to
help to remove a lot of BTRFS_I() calls in btrfs_sync_file().
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of using a inode pointer, use a btrfs_inode pointer in the log
context structure, as this is generally what we need and allows for some
internal APIs to take a btrfs_inode instead, making them more consistent
with most of the code base. This will later allow to help to remove a lot
of BTRFS_I() calls in btrfs_sync_file().
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-6.10-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fix from David Sterba:
"A fix for fast fsync that needs to handle errors during writes after
some COW failure so it does not lead to an inconsistent state"
* tag 'for-6.10-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: ensure fast fsync waits for ordered extents after a write failure
If a write path in COW mode fails, either before submitting a bio for the
new extents or an actual IO error happens, we can end up allowing a fast
fsync to log file extent items that point to unwritten extents.
This is because dropping the extent maps happens when completing ordered
extents, at btrfs_finish_one_ordered(), and the completion of an ordered
extent is executed in a work queue.
This can result in a fast fsync to start logging file extent items based
on existing extent maps before the ordered extents complete, therefore
resulting in a log that has file extent items that point to unwritten
extents, resulting in a corrupt file if a crash happens after and the log
tree is replayed the next time the fs is mounted.
This can happen for both direct IO writes and buffered writes.
For example consider a direct IO write, in COW mode, that fails at
btrfs_dio_submit_io() because btrfs_extract_ordered_extent() returned an
error:
1) We call btrfs_finish_ordered_extent() with the 'uptodate' parameter
set to false, meaning an error happened;
2) That results in marking the ordered extent with the BTRFS_ORDERED_IOERR
flag;
3) btrfs_finish_ordered_extent() queues the completion of the ordered
extent - so that btrfs_finish_one_ordered() will be executed later in
a work queue. That function will drop extent maps in the range when
it's executed, since the extent maps point to unwritten locations
(signaled by the BTRFS_ORDERED_IOERR flag);
4) After calling btrfs_finish_ordered_extent() we keep going down the
write path and unlock the inode;
5) After that a fast fsync starts and locks the inode;
6) Before the work queue executes btrfs_finish_one_ordered(), the fsync
task sees the extent maps that point to the unwritten locations and
logs file extent items based on them - it does not know they are
unwritten, and the fast fsync path does not wait for ordered extents
to complete, which is an intentional behaviour in order to reduce
latency.
For the buffered write case, here's one example:
1) A fast fsync begins, and it starts by flushing delalloc and waiting for
the writeback to complete by calling filemap_fdatawait_range();
2) Flushing the dellaloc created a new extent map X;
3) During the writeback some IO error happened, and at the end io callback
(end_bbio_data_write()) we call btrfs_finish_ordered_extent(), which
sets the BTRFS_ORDERED_IOERR flag in the ordered extent and queues its
completion;
4) After queuing the ordered extent completion, the end io callback clears
the writeback flag from all pages (or folios), and from that moment the
fast fsync can proceed;
5) The fast fsync proceeds sees extent map X and logs a file extent item
based on extent map X, resulting in a log that points to an unwritten
data extent - because the ordered extent completion hasn't run yet, it
happens only after the logging.
To fix this make btrfs_finish_ordered_extent() set the inode flag
BTRFS_INODE_NEEDS_FULL_SYNC in case an error happened for a COW write,
so that a fast fsync will wait for ordered extent completion.
Note that this issues of using extent maps that point to unwritten
locations can not happen for reads, because in read paths we start by
locking the extent range and wait for any ordered extents in the range
to complete before looking for extent maps.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-6.10-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"This update brings a few minor performance improvements, otherwise
there's a lot of refactoring, cleanups and other sort of not user
visible changes.
Performance improvements:
- inline b-tree locking functions, improvement in metadata-heavy
changes
- relax locking on a range that's being reflinked, allows read
operations to run in parallel
- speed up NOCOW write checks (throughput +9% on a sample test)
- extent locking ranges have been reduced in several places, namely
around delayed ref processing
Core:
- more page to folio conversions:
- relocation
- send
- compression
- inline extent handling
- super block write and wait
- extent_map structure optimizations:
- reduced structure size
- code simplifications
- add shrinker for allocated objects, the numbers can go high and
could exhaust memory on smaller systems (reported) as they may
not get an opportunity to be freed fast enough
- extent locking optimizations:
- reduce locking ranges where it does not seem to be necessary and
are safe due to other means of synchronization
- potential improvements due to lower contention,
allocation/freeing and state management operations of extent
state tracking structures
- delayed ref cleanups and simplifications
- updated trace points
- improved error handling, warnings and assertions
- cleanups and refactoring, unification of error handling paths"
* tag 'for-6.10-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (122 commits)
btrfs: qgroup: fix initialization of auto inherit array
btrfs: count super block write errors in device instead of tracking folio error state
btrfs: use the folio iterator in btrfs_end_super_write()
btrfs: convert super block writes to folio in write_dev_supers()
btrfs: convert super block writes to folio in wait_dev_supers()
bio: Export bio_add_folio_nofail to modules
btrfs: remove duplicate included header from fs.h
btrfs: add a cached state to extent_clear_unlock_delalloc
btrfs: push extent lock down in submit_one_async_extent
btrfs: push lock_extent down in cow_file_range()
btrfs: move can_cow_file_range_inline() outside of the extent lock
btrfs: push lock_extent into cow_file_range_inline
btrfs: push extent lock into cow_file_range
btrfs: push extent lock into run_delalloc_cow
btrfs: remove unlock_extent from run_delalloc_compressed
btrfs: push extent lock down in run_delalloc_nocow
btrfs: adjust while loop condition in run_delalloc_nocow
btrfs: push extent lock into run_delalloc_nocow
btrfs: push the extent lock into btrfs_run_delalloc_range
btrfs: lock extent when doing inline extent in compression
...
A comment from Filipe on one of my previous cleanups brought my
attention to a new helper we have for getting the root id of a root,
which makes it easier to read in the code.
The changes where made with the following Coccinelle semantic patch:
// <smpl>
@@
expression E,E1;
@@
(
E->root_key.objectid = E1
|
- E->root_key.objectid
+ btrfs_root_id(E)
)
// </smpl>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor style fixups ]
Signed-off-by: David Sterba <dsterba@suse.com>
We consistently use ->num_bytes everywhere through the delayed ref code,
except in btrfs_ref. Rename btrfs_ref to match all the other code.
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 have this in both btrfs_tree_ref and btrfs_data_ref, which is just
wasting space and making the code more complicated. Move this into
btrfs_ref proper and update all the call sites to do the assignment in
btrfs_ref.
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>
btrfs_ref currently has ->owning_root, and ->ref_root is shared between
the tree ref and data ref, so in order to move that into btrfs_ref
proper I would need to add another root parameter to the initialization
function. This function has too many arguments, and adding another root
will make it easy to make mistakes about which root goes where.
Drop the generic ref init function and statically initialize the
btrfs_ref in every usage. This makes the code easier to read because we
can see what elements we're assigning, and will make the upcoming change
moving the ref_root into the btrfs_ref more clear and less error prone
than adding a new element to the initialization function.
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>
btrfs_page_mkwrite() is a struct vm_operations_struct callback and we
define that structure in file.c. Currently the function is in inode.c and
has to be exported to be used in file.c, which makes no sense because it's
not used anywhere else. So move btrfs_page_mkwrite() from inode.c and into
file.c.
While at it do a few minor style changes:
1) Capitalize the first word of every comment and end each sentence with
punctuation;
2) Avoid splitting some statements into two lines when everything fits in
85 characters or less.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Unify naming of return value to the preferred way.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Unify naming of return value to the preferred way.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Unify naming of return value to the preferred way.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There's a bunch of flags that are purely based on what the file
operations support while also never being conditionally set or unset.
IOW, they're not subject to change for individual files. Imho, such
flags don't need to live in f_mode they might as well live in the fops
structs itself. And the fops struct already has that lonely
mmap_supported_flags member. We might as well turn that into a generic
fop_flags member and move a few flags from FMODE_* space into FOP_*
space. That gets us four FMODE_* bits back and the ability for new
static flags that are about file ops to not have to live in FMODE_*
space but in their own FOP_* space. It's not the most beautiful thing
ever but it gets the job done. Yes, there'll be an additional pointer
chase but hopefully that won't matter for these flags.
I suspect there's a few more we can move into there and that we can also
redirect a bunch of new flag suggestions that follow this pattern into
the fop_flags field instead of f_mode.
Link: https://lore.kernel.org/r/20240328-gewendet-spargel-aa60a030ef74@brauner
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Add a convenience helper to get a fs_info from a VFS inode pointer
instead of open coding the chain or using btrfs_sb() that in some cases
does one more pointer hop. This is implemented as a macro (still with
type checking) so we don't need full definitions of struct btrfs_inode,
btrfs_root or btrfs_fs_info.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When logging an inode and we require to copy items from subvolume leaves
to the log tree, we clone each subvolume leaf and than use that clone to
copy items to the log tree. This is required to avoid possible deadlocks
as stated in commit 796787c978 ("btrfs: do not modify log tree while
holding a leaf from fs tree locked").
The cloning requires allocating an extent buffer (struct extent_buffer)
and then allocating pages (folios) to attach to the extent buffer. This
may be slow in case we are under memory pressure, and since we are doing
the cloning while holding a read lock on a subvolume leaf, it means we
can be blocking other operations on that leaf for significant periods of
time, which can increase latency on operations like creating other files,
renaming files, etc. Similarly because we're under a log transaction, we
may also cause extra delay on other tasks doing an fsync, because syncing
the log requires waiting for tasks that joined a log transaction to exit
the transaction.
So to improve this, for any inode logging operation that needs to copy
items from a subvolume leaf ("full sync" or "copy everything" bit set
in the inode), preallocate a dummy extent buffer before locking any
extent buffer from the subvolume tree, and even before joining a log
transaction, add it to the log context and then use it when we need to
copy items from a subvolume leaf to the log tree. This avoids making
other operations get extra latency when waiting to lock a subvolume
leaf that is used during inode logging and we are under heavy memory
pressure.
The following test script with bonnie++ was used to test this:
$ cat test.sh
#!/bin/bash
DEV=/dev/sdh
MNT=/mnt/sdh
MOUNT_OPTIONS="-o ssd"
MEMTOTAL_BYTES=`free -b | grep Mem: | awk '{ print $2 }'`
NR_DIRECTORIES=20
NR_FILES=20480
DATASET_SIZE=$((MEMTOTAL_BYTES * 2 / 1048576))
DIRECTORY_SIZE=$((MEMTOTAL_BYTES * 2 / NR_FILES))
NR_FILES=$((NR_FILES / 1024))
echo "performance" | \
tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
umount $DEV &> /dev/null
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
bonnie++ -u root -d $MNT \
-n $NR_FILES:$DIRECTORY_SIZE:$DIRECTORY_SIZE:$NR_DIRECTORIES \
-r 0 -s $DATASET_SIZE -b
umount $MNT
The results of this test on a 8G VM running a non-debug kernel (Debian's
default kernel config), were the following.
Before this change:
Version 2.00a ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Name:Size etc /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
debian0 7501M 376k 99 1.4g 96 117m 14 1510k 99 2.5g 95 +++++ +++
Latency 35068us 24976us 2944ms 30725us 71770us 26152us
Version 2.00a ------Sequential Create------ --------Random Create--------
debian0 -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files:max:min /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
20:384100:384100/20 20480 32 20480 58 20480 48 20480 39 20480 56 20480 61
Latency 411ms 11914us 119ms 617ms 10296us 110ms
After this change:
Version 2.00a ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Name:Size etc /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
debian0 7501M 375k 99 1.4g 97 117m 14 1546k 99 2.3g 98 +++++ +++
Latency 35975us 20945us 2144ms 10297us 2217us 6004us
Version 2.00a ------Sequential Create------ --------Random Create--------
debian0 -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files:max:min /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
20:384100:384100/20 20480 35 20480 58 20480 48 20480 40 20480 57 20480 59
Latency 320ms 11237us 77779us 518ms 6470us 86389us
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>
With help of neovim, LSP and clangd we can identify header files that
are not actually needed to be included in the .c files. This is focused
only on removal (with minor fixups), further cleanups are possible but
will require doing the header files properly with forward declarations,
minimized includes and include-what-you-use care.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The block size calculated by i_blocksize from inode is the same as what
we have in fs_info, initalized in inode_init_always(). Unify that to use
the fs_info value everywhere.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The parameter @pg_offset of btrfs_get_extent() is only utilized for
inlined extent, and we already have an ASSERT() and tree-checker, to
make sure we can only get inline extent at file offset 0.
Any invalid inline extent with non-zero file offset would be rejected by
tree-checker in the first place.
Thus the @pg_offset parameter is not really necessary, just remove it.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Although subpage itself is conflicting with higher folio, since subpage
(sectorsize < PAGE_SIZE and nodesize < PAGE_SIZE) means we will never
need higher order folio, there is a hidden pitfall:
- btrfs_page_*() helpers
Those helpers are an abstraction to handle both subpage and non-subpage
cases, which means we're going to pass pages pointers to those helpers.
And since those helpers are shared between data and metadata paths, it's
unavoidable to let them to handle folios, including higher order
folios).
Meanwhile for true subpage case, we should only have a single page
backed folios anyway, thus add a new ASSERT() for btrfs_subpage_assert()
to ensure that.
Also since those helpers are shared between both data and metadata, add
some extra ASSERT()s for data path to make sure we only get single page
backed folio for now.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently, in struct extent_map, we use an unsigned int (32 bits) to
identify the compression type of an extent and an unsigned long (64 bits
on a 64 bits platform, 32 bits otherwise) for flags. We are only using
6 different flags, so an unsigned long is excessive and we can use flags
to identify the compression type instead of using a dedicated 32 bits
field.
We can easily have tens or hundreds of thousands (or more) of extent maps
on busy and large filesystems, specially with compression enabled or many
or large files with tons of small extents. So it's convenient to have the
extent_map structure as small as possible in order to use less memory.
So remove the compression type field from struct extent_map, use flags
to identify the compression type and shorten the flags field from an
unsigned long to a u32. This saves 8 bytes (on 64 bits platforms) and
reduces the size of the structure from 136 bytes down to 128 bytes, using
now only two cache lines, and increases the number of extent maps we can
have per 4K page from 30 to 32. By using a u32 for the flags instead of
an unsigned long, we no longer use test_bit(), set_bit() and clear_bit(),
but that level of atomicity is not needed as most flags are never cleared
once set (before adding an extent map to the tree), and the ones that can
be cleared or set after an extent map is added to the tree, are always
performed while holding the write lock on the extent map tree, while the
reader holds a lock on the tree or tests for a flag that never changes
once the extent map is in the tree (such as compression flags).
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
As a cleanup and preparation for future folio migration, this patch
would replace all page->private to folio version. This includes:
- PagePrivate()
-> folio_test_private()
- page->private
-> folio_get_private()
- attach_page_private()
-> folio_attach_private()
- detach_page_private()
-> folio_detach_private()
Since we're here, also remove the forced cast on page->private, since
it's (void *) already, we don't really need to do the cast.
For now even if we missed some call sites, it won't cause any problem
yet, as we're only using order 0 folio (single page), thus all those
folio/page flags should be synced.
But for the future conversion to utilize higher order folio, the page
<-> folio flag sync is no longer guaranteed, thus we have to migrate to
utilize folio flags.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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-6.7-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"Some fixes to quota accounting code, mostly around error handling and
correctness:
- free reserves on various error paths, after IO errors or
transaction abort
- don't clear reserved range at the folio release time, it'll be
properly cleared after final write
- fix integer overflow due to int used when passing around size of
freed reservations
- fix a regression in squota accounting that missed some cases with
delayed refs"
* tag 'for-6.7-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: ensure releasing squota reserve on head refs
btrfs: don't clear qgroup reserved bit in release_folio
btrfs: free qgroup pertrans reserve on transaction abort
btrfs: fix qgroup_free_reserved_data int overflow
btrfs: free qgroup reserve when ORDERED_IOERR is set
