In ext4_bio_write_page(), if the memory allocation for the struct
ext4_io_page fails, it returns with the page's PageWriteback flag set.
This will end up causing the page not to skip writeback in
WB_SYNC_NONE mode, and in WB_SYNC_ALL mode (i.e., on a sync, fsync, or
umount) the writeback daemon will get stuck forever on the
wait_on_page_writeback() function in write_cache_pages_da().
Or, if journalling is enabled and the file gets deleted, it the
journal thread can get stuck in journal_finish_inode_data_buffers()
call to filemap_fdatawait().
Another place where things can get hung up is in
truncate_inode_pages(), called out of ext4_evict_inode().
Fix this by not setting PageWriteback until after we have successfully
allocated the struct ext4_io_page.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Move the initialization of all of the fields of the mpd structure to
write_cache_pages_da(). This simplifies the code considerably.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
If we have accumulated a contiguous region of memory to be written
out, and the next page can added to this region, don't bother locking
(and then unlocking the page) before writing out the memory. In the
unlikely event that the next page was being written back by some other
CPU, we can also skip waiting that page to finish writeback.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Because the ext4 page writeback codepath had been prematurely calling
clear_page_dirty_for_io(), if it turned out that a particular page
couldn't be written out during a particular pass of
write_cache_pages_da(), the page would have to get redirtied by
calling redirty_pages_for_writeback(). Not only was this wasted work,
but redirty_page_for_writeback() would increment wbc->pages_skipped to
signal to writeback_sb_inodes() that buffers were locked, and that it
should skip this inode until later.
Since this signal was incorrect in ext4's case --- which was caused by
ext4's historically incorrect use of write_cache_pages() ---
ext4_da_writepages() saved and restored wbc->skipped_pages to avoid
confusing writeback_sb_inodes().
Now that we've fixed ext4 to call clear_page_dirty_for_io() right
before initiating the page I/O, we can nuke the page_skipped
save/restore hackery, and breathe a sigh of relief.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Move when we call clear_page_dirty_for_io() to just before we actually
write the page. This simplifies the code somewhat, and avoids marking
pages as clean and then needing to remark them as dirty later.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Eliminate duplicate code, unneeded variables, etc., to make it easier
to understand the code. No behavioral changes were made in this patch.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Fold the __mpage_da_writepage() function into write_cache_pages_da().
This will give us opportunities to clean up and simplify the resulting
code.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Now that we've fixed the file corruption bug in commit d50bdd5aa5,
it's time to enable mblk_io_submit by default.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
If ext4_da_block_invalidatepages() is called because of a
failure from ext4_map_blocks() in mpage_da_map_and_submit(),
it's supposed to clean up -- including unlock -- all the
pages in the mpd structure. But these values may not match
up, even on a system in which block size == page size:
mpd->b_blocknr != mpd->first_page
mpd->b_size != (mpd->next_page - mpd->first_page)
ext4_da_block_invalidatepages() has been using b_blocknr and
b_size; this patch changes it to use first_page and
next_page.
Tested: I injected a small number (5%) of failures in
ext4_map_blocks() in the case that the flags contain
EXT4_GET_BLOCKS_DELALLOC_RESERVE, and ran fsstress on this
kernel. Without this patch, I got hung tasks every time.
With this patch, I see no hangs in many runs of fsstress.
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
In mpage_da_map_and_submit(), if we have a delayed block
allocation failure from ext4_map_blocks(), we need to mark
the IO as complete, by setting
mpd->io_done = 1;
Otherwise, we could end up submitting the pages in an outer
loop; since they are unlocked on mapping failure in
ext4_da_block_invalidatepages(), this will cause a bug check
in mpage_da_submit_io().
I tested this by injected failures into ext4_map_blocks().
Without this patch, a simple fsstress run will bug check;
with the patch, it works fine.
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
In ext4_mb_check_group_pa(), the current preallocation space is
replaced with a new preallocation space when the two have the same
distance from the goal block.
This doesn't actually gain us anything, so change things so that the
function only switches to the new preallocation group if its distance
from the goal block is strictly smaller than the current preallocaiton
group's distance from the goal block.
Signed-off-by: Coly Li <bosong.ly@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This patch adds comments to ext4_mb_mark_free_simple to make it more
understandable.
Signed-off-by: Coly Li <bosong.ly@taobao.com>
Cc: Alex Tomas <alex@clusterfs.com>
Cc: Theodore Tso <tytso@google.com>
In __mb_check_buddy(), look at the code below:
591 fstart = -1;
592 buddy = mb_find_buddy(e4b, 0, &max);
593 for (i = 0; i < max; i++) {
594 if (!mb_test_bit(i, buddy)) {
595 MB_CHECK_ASSERT(i >= e4b->bd_info->bb_first_free);
596 if (fstart == -1) {
597 fragments++;
598 fstart = i;
599 }
600 continue;
601 }
602 fstart = -1;
603 /* check used bits only */
604 for (j = 0; j < e4b->bd_blkbits + 1; j++) {
605 buddy2 = mb_find_buddy(e4b, j, &max2);
606 k = i >> j;
607 MB_CHECK_ASSERT(k < max2);
608 MB_CHECK_ASSERT(mb_test_bit(k, buddy2));
609 }
610 }
611 MB_CHECK_ASSERT(!EXT4_MB_GRP_NEED_INIT(e4b->bd_info));
612 MB_CHECK_ASSERT(e4b->bd_info->bb_fragments == fragments);
613
614 grp = ext4_get_group_info(sb, e4b->bd_group);
615 buddy = mb_find_buddy(e4b, 0, &max);
On line 592, buddy is fetched by mb_find_buddy() with order 0, between
line 593 to line 615, buddy is not changed, therefore there is
no need to fetch buddy again from mb_find_buddy() with order 0 again.
We can safely remove the second mb_find_buddy() on line 615.
Signed-off-by: Coly Li <bosong.ly@taobao.com>
Cc: Alex Tomas <alex@clusterfs.com>
Cc: Theodore Tso <tytso@google.com>
Current code calculate max no matter whether order is zero, it's
unnecessary. This cleanup patch sets max to "1 << (e4b->bd_blkbits
+ 3)" only when order == 0.
Signed-off-by: Coly Li <bosong.ly@taobao.com>
Cc: Alex Tomas <alex@clusterfs.com>
Cc: Theodore Tso <tytso@google.com>
There's no good reason to require the extra step of providing
a mount option for acl or user_xattr once the feature is configured
on; no other filesystem that I know of requires this.
Userspace patches have set these options in default mount options,
and this patch makes them default in the kernel. At some point
we can start to deprecate the options, perhaps.
For now I've removed default mount option checks in show_options()
to be explicit about what's set, since it's changing the default,
but I'm open to alternatives if desired.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Discard granularity tells us the minimum size of extent that can be
discarded by the device. If the user supplies a minimum extent that
should be discarded (range.minlen) which is smaller than the discard
granularity, increase minlen to the discard granularity, since there's
no point submitting trim requests that the device will reject anyway.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
For a device that does not support discard, the FITRIM ioctl returns
-EOPNOTSUPP when blkdev_issue_discard() returns this error code, which
is how the user is informed that the device does not support discard.
If there are no suitable free extents to be trimmed, then FITRIM will
return success even though the device does not support discard, which
could confuse the user. So check explicitly if the device supports
discard and return an error code at the beginning of the FITRIM ioctl
processing.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
I cannot disable inode-read-ahead feature of ext4 (on 2.6.37):
# echo 0 > /sys/fs/ext4/sda2/inode_readahead_blks
bash: echo: write error: Invalid argument
On a server with lots of small files and random access this read-ahead makes
performance worse, and I'd like to disable it. I work around this problem
by using value of 1, but it still reads an extra block.
This patch fixes the problem by checking for zero explicitly.
Signed-off-by: Alexander V. Lukyanov <lav@netis.ru>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This patch fixes the warning "Using plain integer as NULL pointer",
generated by sparse, by replacing the offending 0s with NULL.
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Compile 2.6.38-rc1 with turning EXT4FS_DEBUG on,
we get following compile warnings. This patch fixes them.
CC fs/ext4/hash.o
CC fs/ext4/resize.o
fs/ext4/resize.c: In function 'setup_new_group_blocks':
fs/ext4/resize.c:233:2: warning: format '%#04llx' expects type 'long long
unsigned int', but argument 3 has type 'long unsigned int'
fs/ext4/resize.c:251:2: warning: format '%#04llx' expects type 'long long
unsigned int', but argument 3 has type 'long unsigned int'
CC fs/ext4/extents.o
CC fs/ext4/ext4_jbd2.o
CC fs/ext4/migrate.o
Reported-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
ext4 has a data corruption case when doing non-block-aligned
asynchronous direct IO into a sparse file, as demonstrated
by xfstest 240.
The root cause is that while ext4 preallocates space in the
hole, mappings of that space still look "new" and
dio_zero_block() will zero out the unwritten portions. When
more than one AIO thread is going, they both find this "new"
block and race to zero out their portion; this is uncoordinated
and causes data corruption.
Dave Chinner fixed this for xfs by simply serializing all
unaligned asynchronous direct IO. I've done the same here.
The difference is that we only wait on conversions, not all IO.
This is a very big hammer, and I'm not very pleased with
stuffing this into ext4_file_write(). But since ext4 is
DIO_LOCKING, we need to serialize it at this high level.
I tried to move this into ext4_ext_direct_IO, but by then
we have the i_mutex already, and we will wait on the
work queue to do conversions - which must also take the
i_mutex. So that won't work.
This was originally exposed by qemu-kvm installing to
a raw disk image with a normal sector-63 alignment. I've
tested a backport of this patch with qemu, and it does
avoid the corruption. It is also quite a lot slower
(14 min for package installs, vs. 8 min for well-aligned)
but I'll take slow correctness over fast corruption any day.
Mingming suggested that we can track outstanding
conversions, and wait on those so that non-sparse
files won't be affected, and I've implemented that here;
unaligned AIO to nonsparse files won't take a perf hit.
[tytso@mit.edu: Keep the mutex as a hashed array instead
of bloating the ext4 inode]
[tytso@mit.edu: Fix up namespace issues so that global
variables are protected with an "ext4_" prefix.]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
In 2.6.37 I was running into oopses with repeated module
loads & unloads. I tracked this down to:
fb1813f4 ext4: use dedicated slab caches for group_info structures
(this was in addition to the features advert unload problem)
The kstrdup & subsequent kfree of the cache name was causing
a double free. In slub, at least, if I read it right it allocates
& frees the name itself, slab seems to do something different...
so in slub I think we were leaking -our- cachep->name, and double
freeing the one allocated by slub.
After getting lost in slab/slub/slob a bit, I just looked at other
sized-caches that get allocated. jbd2, biovec, sgpool all do it
more or less the way jbd2 does. Below patch follows the jbd2
method of dynamically allocating a cache at mount time from
a list of static names.
(This might also possibly fix a race creating the caches with
parallel mounts running).
[Folded in a fix from Dan Carpenter which fixed an off-by-one error in
the original patch]
Cc: stable@kernel.org
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This fixes a corruption problem with the multi-block
writepages submittal change for ext4, from commit
bd2d0210cf ("ext4: use bio
layer instead of buffer layer in mpage_da_submit_io").
(Note that this corruption is not present in 2.6.37 on
ext4, because the corruption was detected after the
feature was merged in 2.6.37-rc1, and so it was turned
off by adding a non-default mount option,
mblk_io_submit. With this commit, which hopefully
fixes the last of the bugs with this feature, we'll be
able to turn on this performance feature by default in
2.6.38, and remove the mblk_io_submit option.)
The ext4 code path to bundle multiple pages for
writeback in ext4_bio_write_page() had a bug: we should
be clearing buffer head dirty flags *before* we submit
the bio, not in the completion routine.
The patch below was tested on 2.6.37 under KVM with the
postgresql script which was submitted by Jon Nelson as
documented in commit 1449032be1.
Without the patch, I'd hit the corruption problem about
50-70% of the time. With the patch, I executed the
script > 100 times with no corruption seen.
I also fixed a bug to make sure ext4_end_bio() doesn't
dereference the bio after the bio_put() call.
Reported-by: Jon Nelson <jnelson@jamponi.net>
Reported-by: Matthias Bayer <jackdachef@gmail.com>
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
Ext4 features interface was not properly unregistered which led to
problems while unloading/reloading ext4 module. This commit fixes that by
adding proper kobject unregistration code into ext4_exit_fs() as well as
fail-path of ext4_init_fs()
Reported-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
https://bugzilla.kernel.org/show_bug.cgi?id=27652
If the lazyinit thread is running, the teardown function
ext4_destroy_lazyinit_thread() has problems:
ext4_clear_request_list();
while (ext4_li_info->li_task) {
wake_up(&ext4_li_info->li_wait_daemon);
wait_event(ext4_li_info->li_wait_task,
ext4_li_info->li_task == NULL);
}
Clearing the request list will cause the thread to exit and free
ext4_li_info, so then we're waiting on something which is getting
freed.
Fix this up by making the thread respond to kthread_stop, and exit,
without the need to wait for that exit in some other homegrown way.
Cc: stable@kernel.org
Reported-and-Tested-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Currently all filesystems except XFS implement fallocate asynchronously,
while XFS forced a commit. Both of these are suboptimal - in case of O_SYNC
I/O we really want our allocation on disk, especially for the !KEEP_SIZE
case where we actually grow the file with user-visible zeroes. On the
other hand always commiting the transaction is a bad idea for fast-path
uses of fallocate like for example in recent Samba versions. Given
that block allocation is a data plane operation anyway change it from
an inode operation to a file operation so that we have the file structure
available that lets us check for O_SYNC.
This also includes moving the code around for a few of the filesystems,
and remove the already unnedded S_ISDIR checks given that we only wire
up fallocate for regular files.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Instead of various home grown checks that might need updates for new
flags just check for any bit outside the mask of the features supported
by the filesystem. This makes the check future proof for any newly
added flag.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block: (43 commits)
block: ensure that completion error gets properly traced
blktrace: add missing probe argument to block_bio_complete
block cfq: don't use atomic_t for cfq_group
block cfq: don't use atomic_t for cfq_queue
block: trace event block fix unassigned field
block: add internal hd part table references
block: fix accounting bug on cross partition merges
kref: add kref_test_and_get
bio-integrity: mark kintegrityd_wq highpri and CPU intensive
block: make kblockd_workqueue smarter
Revert "sd: implement sd_check_events()"
block: Clean up exit_io_context() source code.
Fix compile warnings due to missing removal of a 'ret' variable
fs/block: type signature of major_to_index(int) to major_to_index(unsigned)
block: convert !IS_ERR(p) && p to !IS_ERR_NOR_NULL(p)
cfq-iosched: don't check cfqg in choose_service_tree()
fs/splice: Pull buf->ops->confirm() from splice_from_pipe actors
cdrom: export cdrom_check_events()
sd: implement sd_check_events()
sr: implement sr_check_events()
...
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (41 commits)
fs: add documentation on fallocate hole punching
Gfs2: fail if we try to use hole punch
Btrfs: fail if we try to use hole punch
Ext4: fail if we try to use hole punch
Ocfs2: handle hole punching via fallocate properly
XFS: handle hole punching via fallocate properly
fs: add hole punching to fallocate
vfs: pass struct file to do_truncate on O_TRUNC opens (try #2)
fix signedness mess in rw_verify_area() on 64bit architectures
fs: fix kernel-doc for dcache::prepend_path
fs: fix kernel-doc for dcache::d_validate
sanitize ecryptfs ->mount()
switch afs
move internal-only parts of ncpfs headers to fs/ncpfs
switch ncpfs
switch 9p
pass default dentry_operations to mount_pseudo()
switch hostfs
switch affs
switch configfs
...
pr_warning_ratelimited() doesn't exist.
Also include printk.h, which defines these things.
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Ext4 doesn't have the ability to punch holes yet, so make sure we return
EOPNOTSUPP if we try to use hole punching through fallocate. This support can
be added later. Thanks,
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
As Al Viro pointed out path resolution during Q_QUOTAON calls to quotactl
is prone to deadlocks. We hold s_umount semaphore for reading during the
path resolution and resolution itself may need to acquire the semaphore
for writing when e. g. autofs mountpoint is passed.
Solve the problem by performing the resolution before we get hold of the
superblock (and thus s_umount semaphore). The whole thing is complicated
by the fact that some filesystems (OCFS2) ignore the path argument. So to
distinguish between filesystem which want the path and which do not we
introduce new .quota_on_meta callback which does not get the path. OCFS2
then uses this callback instead of old .quota_on.
CC: Al Viro <viro@ZenIV.linux.org.uk>
CC: Christoph Hellwig <hch@lst.de>
CC: Ted Ts'o <tytso@mit.edu>
CC: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (44 commits)
ext4: fix trimming starting with block 0 with small blocksize
ext4: revert buggy trim overflow patch
ext4: don't pass entire map to check_eofblocks_fl
ext4: fix memory leak in ext4_free_branches
ext4: remove ext4_mb_return_to_preallocation()
ext4: flush the i_completed_io_list during ext4_truncate
ext4: add error checking to calls to ext4_handle_dirty_metadata()
ext4: fix trimming of a single group
ext4: fix uninitialized variable in ext4_register_li_request
ext4: dynamically allocate the jbd2_inode in ext4_inode_info as necessary
ext4: drop i_state_flags on architectures with 64-bit longs
ext4: reorder ext4_inode_info structure elements to remove unneeded padding
ext4: drop ec_type from the ext4_ext_cache structure
ext4: use ext4_lblk_t instead of sector_t for logical blocks
ext4: replace i_delalloc_reserved_flag with EXT4_STATE_DELALLOC_RESERVED
ext4: fix 32bit overflow in ext4_ext_find_goal()
ext4: add more error checks to ext4_mkdir()
ext4: ext4_ext_migrate should use NULL not 0
ext4: Use ext4_error_file() to print the pathname to the corrupted inode
ext4: use IS_ERR() to check for errors in ext4_error_file
...
When s_first_data_block is not zero (which happens e.g. when block size is 1KB)
and trim ioctl is called to start trimming from block 0, the math in
ext4_get_group_no_and_offset() overflows. The overall result is that ioctl
returns EINVAL which is kind of unexpected and we probably don't want
userspace tools to bother with internal details of filesystem structure.
So just silently increase starting offset (and shorten length) when starting
block is below s_first_data_block.
CC: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Since check_eofblocks_fl() only uses the m_lblk portion of the map
structure, we may as well pass that directly, rather than passing the
entire map, which IMHO obfuscates what parameters check_eofblocks_fl()
cares about. Not a big deal, but seems tidier and less confusing, to
me.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Commit 40389687 moved a call to ext4_forget() out of
ext4_free_branches and let ext4_free_blocks() handle calling
bforget(). But that change unfortunately did not replace the call to
ext4_forget() with brelse(), which was needed to drop the in-use count
of the indirect block's buffer head, which lead to a memory leak when
deleting files that used indirect blocks. Fix this.
Thanks to Hugh Dickins for pointing this out.
Cc: stable@kernel.org
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This function was never implemented, except for a BUG_ON which was
tripping when ext4 is run without a journal. The problem is that
although the comment asserts that "truncate (which is the only way to
free block) discards all preallocations", ext4_free_blocks() is also
called in various error recovery paths when blocks have been
allocated, but for various reasons, we were not able to use those data
blocks (for example, because we ran out of memory while trying to
manipulate the extent tree, or some other similar situation).
In addition to the fact that this function isn't implemented except
for the incorrect BUG_ON, the single caller of this function,
ext4_free_blocks(), doesn't use it all if the journal is enabled.
So remove the (stub) function entirely for now. If we decide it's
better to add it back, it's only going to be useful with a relatively
large number of code changes anyway.
Google-Bug-Id: 3236408
Cc: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Ted first found the bug when running 2.6.36 kernel with dioread_nolock
mount option that xfstests #13 complained about wrong file size during fsck.
However, the bug exists in the older kernels as well although it is
somehow harder to trigger.
The problem is that ext4_end_io_work() can happen after we have truncated an
inode to a smaller size. Then when ext4_end_io_work() calls
ext4_convert_unwritten_extents(), we may reallocate some blocks that have
been truncated, so the inode size becomes inconsistent with the allocated
blocks.
The following patch flushes the i_completed_io_list during truncate to reduce
the risk that some pending end_io requests are executed later and convert
already truncated blocks to initialized.
Note that although the fix helps reduce the problem a lot there may still
be a race window between vmtruncate() and ext4_end_io_work(). The fundamental
problem is that if vmtruncate() is called without either i_mutex or i_alloc_sem
held, it can race with an ongoing write request so that the io_end request is
processed later when the corresponding blocks have been truncated.
Ted and I have discussed the problem offline and we saw a few ways to fix
the race completely:
a) We guarantee that i_mutex lock and i_alloc_sem write lock are both hold
whenever vmtruncate() is called. The i_mutex lock prevents any new write
requests from entering writeback and the i_alloc_sem prevents the race
from ext4_page_mkwrite(). Currently we hold both locks if vmtruncate()
is called from do_truncate(), which is probably the most common case.
However, there are places where we may call vmtruncate() without holding
either i_mutex or i_alloc_sem. I would like to ask for other people's
opinions on what locks are expected to be held before calling vmtruncate().
There seems a disagreement among the callers of that function.
b) We change the ext4 write path so that we change the extent tree to contain
the newly allocated blocks and update i_size both at the same time --- when
the write of the data blocks is completed.
c) We add some additional locking to synchronize vmtruncate() and
ext4_end_io_work(). This approach may have performance implications so we
need to be careful.
All of the above proposals may require more substantial changes, so
we may consider to take the following patch as a bandaid.
Signed-off-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Call ext4_std_error() in various places when we can't bail out
cleanly, so the file system can be marked as in error.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
When ext4_trim_fs() is called to trim a part of a single group, the
logic will wrongly set last block of the interval to 'len' instead
of 'first_block + len'. Thus a shorter interval is possibly trimmed.
Fix it.
CC: Lukas Czerner <lczerner@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
fs/ext4/super.c: In function 'ext4_register_li_request':
fs/ext4/super.c:2936: warning: 'ret' may be used uninitialized in this function
It looks buggy to me, too.
Cc: Lukas Czerner <lczerner@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Replace the jbd2_inode structure (which is 48 bytes) with a pointer
and only allocate the jbd2_inode when it is needed --- that is, when
the file system has a journal present and the inode has been opened
for writing. This allows us to further slim down the ext4_inode_info
structure.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
We can store the dynamic inode state flags in the high bits of
EXT4_I(inode)->i_flags, and eliminate i_state_flags. This saves 8
bytes from the size of ext4_inode_info structure, which when
multiplied by the number of the number of in the inode cache, can save
a lot of memory.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
By reordering the elements in the ext4_inode_info structure, we can
reduce the padding needed on an x86_64 system by 16 bytes.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
