Commit Graph

240 Commits

Author SHA1 Message Date
Josef Bacik
17de39ac17 Btrfs: fix page leak when allocing extent buffers
If we happen to alloc a extent buffer and then alloc a page and notice that
page is already attached to an extent buffer, we will only unlock it and
free our existing eb.  Any pages currently attached to that eb will be
properly freed, but we don't do the page_cache_release() on the page where
we noticed the other extent buffer which can cause us to leak pages and I
hope cause the weird issues we've been seeing in this area.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-05-04 15:16:06 -04:00
Josef Bacik
5cf1ab5613 Btrfs: always store the mirror we read the eb from
A user reported a panic where we were trying to fix a bad mirror but the
mirror number we were giving was 0, which is invalid.  This is because we
don't do the transid verification until after the read, so as far as the
read code is concerned the read was a success.  So instead store the mirror
we read from so that if there is some failure post read we know which mirror
to try next and which mirror needs to be fixed if we find a good copy of the
block.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2012-04-18 19:22:30 +02:00
Li Zefan
cdc6a39525 Btrfs: avoid possible use-after-free in clear_extent_bit()
clear_extent_bit()
{
    next_node = rb_next(&state->rb_node);
    ...
    clear_state_bit(state);  <-- this may free next_node
    if (next_node) {
        state = rb_entry(next_node);
        ...
    }
}

clear_state_bit() calls merge_state() which may free the next node
of the passing extent_state, so clear_extent_bit() may end up
referencing freed memory.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-18 19:22:18 +02:00
Li Zefan
8e52acf704 Btrfs: retrurn void from clear_state_bit
Currently it returns a set of bits that were cleared, but this return
value is not used at all.

Moreover it doesn't seem to be useful, because we may clear the bits
of a few extent_states, but only the cleared bits of last one is
returned.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-18 19:22:16 +02:00
Tsutomu Itoh
e627ee7bcd Btrfs: check return value of bio_alloc() properly
bio_alloc() has the possibility of returning NULL.
So, it is necessary to check the return value.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-04-12 16:03:56 -04:00
Chris Mason
d95603b262 Btrfs: fix uninit variable in repair_eb_io_failure
We'd have to be passing bogus extent buffers for this uninit variable to
actually be used, but set it to zero just in case.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-04-12 15:55:15 -04:00
Chris Mason
1d4284bd6e Merge branch 'error-handling' into for-linus
Conflicts:
	fs/btrfs/ctree.c
	fs/btrfs/disk-io.c
	fs/btrfs/extent-tree.c
	fs/btrfs/extent_io.c
	fs/btrfs/extent_io.h
	fs/btrfs/inode.c
	fs/btrfs/scrub.c

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-03-28 20:31:37 -04:00
Josef Bacik
ea46679408 Btrfs: deal with read errors on extent buffers differently
Since we need to read and write extent buffers in their entirety we can't use
the normal bio_readpage_error stuff since it only works on a per page basis.  So
instead make it so that if we see an io error in endio we just mark the eb as
having an IO error and then in btree_read_extent_buffer_pages we will manually
try other mirrors and then overwrite the bad mirror if we find a good copy.
This works with larger than page size blocks.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-03-26 21:57:36 -04:00
Chris Mason
a098d8e8ee Btrfs: loop waiting on writeback
lock_extent_buffer_for_io needs to loop around and make sure the
writeback bits are not set.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-03-26 17:04:23 -04:00
Josef Bacik
0b32f4bbb4 Btrfs: ensure an entire eb is written at once
This patch simplifies how we track our extent buffers.  Previously we could exit
writepages with only having written half of an extent buffer, which meant we had
to track the state of the pages and the state of the extent buffers differently.
Now we only read in entire extent buffers and write out entire extent buffers,
this allows us to simply set bits in our bflags to indicate the state of the eb
and we no longer have to do things like track uptodate with our iotree.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-03-26 17:04:23 -04:00
Josef Bacik
5df4235ea1 Btrfs: introduce mark_extent_buffer_accessed
Because an eb can have multiple pages we need to make sure that all pages within
the eb are markes as accessed, since releasepage can be called against any page
in the eb.  This will keep us from possibly evicting hot eb's when we're doing
larger than pagesize eb's.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2012-03-26 16:51:09 -04:00
Josef Bacik
3083ee2e18 Btrfs: introduce free_extent_buffer_stale
Because btrfs cow's we can end up with extent buffers that are no longer
necessary just sitting around in memory.  So instead of evicting these pages, we
could end up evicting things we actually care about.  Thus we have
free_extent_buffer_stale for use when we are freeing tree blocks.  This will
make it so that the ref for the eb being in the radix tree is dropped as soon as
possible and then is freed when the refcount hits 0 instead of waiting to be
released by releasepage.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2012-03-26 16:51:08 -04:00
Josef Bacik
115391d231 Btrfs: only use the existing eb if it's count isn't 0
We can run into a problem where we find an eb for our existing page already on
the radix tree but it has a ref count of 0.  It hasn't yet been removed by RCU
yet so this can cause issues where we will use the EB after free.  So do
atomic_inc_not_zero on the exists->refs and if it is zero just do
synchronize_rcu() and try again.  We won't have to worry about new allocators
coming in since they will block on the page lock at this point.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2012-03-26 16:51:08 -04:00
Josef Bacik
4f2de97ace Btrfs: set page->private to the eb
We spend a lot of time looking up extent buffers from pages when we could just
store the pointer to the eb the page is associated with in page->private.  This
patch does just that, and it makes things a little simpler and reduces a bit of
CPU overhead involved with doing metadata IO.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2012-03-26 16:51:07 -04:00
Chris Mason
727011e07c Btrfs: allow metadata blocks larger than the page size
A few years ago the btrfs code to support blocks lager than
the page size was disabled to fix a few corner cases in the
page cache handling.  This fixes the code to properly support
large metadata blocks again.

Since current kernels will crash early and often with larger
metadata blocks, this adds an incompat bit so that older kernels
can't mount it.

This also does away with different blocksizes for nodes and leaves.
You get a single block size for all tree blocks.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-03-26 16:50:37 -04:00
Jeff Mahoney
79787eaab4 btrfs: replace many BUG_ONs with proper error handling
btrfs currently handles most errors with BUG_ON. This patch is a work-in-
 progress but aims to handle most errors other than internal logic
 errors and ENOMEM more gracefully.

 This iteration prevents most crashes but can run into lockups with
 the page lock on occasion when the timing "works out."

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
2012-03-22 11:52:54 +01:00
Jeff Mahoney
3fbe5c02ae btrfs: split extent_state ops
set_extent_bit can do exclusive locking but only when called by lock_extent*,

 Drop the exclusive bits argument except when called by lock_extent.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
2012-03-22 01:45:35 +01:00
Jeff Mahoney
d0082371cf btrfs: drop gfp_t from lock_extent
lock_extent and unlock_extent are always called with GFP_NOFS, drop the
 argument and use GFP_NOFS consistently.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
2012-03-22 01:45:35 +01:00
Jeff Mahoney
143bede527 btrfs: return void in functions without error conditions
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
2012-03-22 01:45:34 +01:00
Jeff Mahoney
355808c296 btrfs: ->submit_bio_hook error push-up
This pushes failures from the submit_bio_hook callbacks,
btrfs_submit_bio_hook and btree_submit_bio_hook into the callers, including
callers of submit_one_bio where it catches the failures with BUG_ON.

It also pushes up through the ->readpage_io_failed_hook to
end_bio_extent_writepage where the error is already caught with BUG_ON.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
2012-03-22 01:45:34 +01:00
Jeff Mahoney
3444a97255 btrfs: Factor out tree->ops->merge_bio_hook call
In submit_extent_page, there's a visually noisy if statement that, in
the midst of other conditions, does the tree dependency for tree->ops
and tree->ops->merge_bio_hook before calling it, and then another
condition afterwards. If an error is returned from merge_bio_hook,
there's no way to catch it. It's considered a routine "1" return
value instead of a failure.

This patch factors out the dependency check into a new local merge_bio
routine and BUG's on an error. The if statement is less noisy as a side-
effect.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
2012-03-22 01:45:33 +01:00
Jeff Mahoney
6763af84a6 btrfs: Remove set bits return from clear_extent_bit
There is only one caller of clear_extent_bit that checks the return value
and it only checks if it's negative. Since there are no users of the
returned bits functionality of clear_extent_bit, stop returning it
and avoid complicating error handling.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
2012-03-22 01:45:32 +01:00
Jeff Mahoney
c2d904e086 btrfs: Catch locking failures in {set,clear,convert}_extent_bit
The *_state functions can only return 0 or -EEXIST. This patch addresses
the cases where those functions returning -EEXIST represent a locking
failure. It handles them by panicking with an appropriate error message.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
2012-03-22 01:45:30 +01:00
Chris Mason
5065319052 Btrfs: clear the extent uptodate bits during parent transid failures
If btrfs reads a block and finds a parent transid mismatch, it clears
the uptodate flags on the extent buffer, and the pages inside it.  But
we only clear the uptodate bits in the state tree if the block straddles
more than one page.

This is from an old optimization from to reduce contention on the extent
state tree.  But it is buggy because the code that retries a read from
a different copy of the block is going to find the uptodate state bits
set and skip the IO.

The end result of the bug is that we'll never actually read the good
copy (if there is one).

The fix here is to always clear the uptodate state bits, which is safe
because this code is only called when the parent transid fails.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-02-23 10:43:45 -05:00
Liu Bo
692e5759a4 Btrfs: be less strict on finding next node in clear_extent_bit
In clear_extent_bit, it is enough that next node is adjacent in tree level.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
2012-02-21 16:02:10 +01:00
Liu Bo
9d47c7671d Btrfs: kick out redundant stuff in convert_extent_bit
clear_state_bit will do merge_state for us, so kick out the redundant one.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
2012-02-16 17:23:17 +01:00
Liu Bo
0449314a9c Btrfs: skip states when they does not contain bits to clear
Clearing a range's bits is different with setting them, since we don't
need to touch them when states do not contain bits we want.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
2012-02-16 17:23:17 +01:00
Tsutomu Itoh
285190d99f Btrfs: check return value of lookup_extent_mapping() correctly
This patch corrects error checking of lookup_extent_mapping().

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
2012-02-16 17:23:17 +01:00
Tsutomu Itoh
013bd4c336 Btrfs: fix return value check of extent_io_ops
This patch adds the check on the return value of extent_io_ops.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
2012-02-16 17:23:16 +01:00
Jeff Mahoney
87826df0ec btrfs: delalloc for page dirtied out-of-band in fixup worker
We encountered an issue that was easily observable on s/390 systems but
 could really happen anywhere. The timing just seemed to hit reliably
 on s/390 with limited memory.

 The gist is that when an unexpected set_page_dirty() happened, we'd
 run into the BUG() in btrfs_writepage_fixup_worker since it wasn't
 properly set up for delalloc.

 This patch does the following:
 - Performs the missing delalloc in the fixup worker
 - Allow the start hook to return -EBUSY which informs __extent_writepage
   that it should mark the page skipped and not to redirty it. This is
   required since the fixup worker can fail with -ENOSPC and the page
   will have already been redirtied. That causes an Oops in
   drop_outstanding_extents later. Retrying the fixup worker could
   lead to an infinite loop. Deferring the page redirty also saves us
   some cycles since the page would be stuck in a resubmit-redirty loop
   until the fixup worker completes. It's not harmful, just wasteful.
 - If the fixup worker fails, we mark the page and mapping as errored,
   and end the writeback, similar to what we would do had the page
   actually been submitted to writeback.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
2012-02-15 16:40:25 +01:00
Mitch Harder
8bedd51b61 Btrfs: Check for NULL page in extent_range_uptodate
A user has encountered a NULL pointer kernel oops in btrfs when
encountering media errors.  The problem has been identified
as an unhandled NULL pointer returned from find_get_page().
This modification simply checks for a NULL page, and returns
with an error if found (the extent_range_uptodate() function
returns 1 on errors).

After testing this patch, the user reported that the error with
the NULL pointer oops was solved.  However, there is still a
remaining problem with a thread becoming stuck in
wait_on_page_locked(page) in the read_extent_buffer_pages(...)
function in extent_io.c

       for (i = start_i; i < num_pages; i++) {
               page = extent_buffer_page(eb, i);
               wait_on_page_locked(page);
               if (!PageUptodate(page))
                       ret = -EIO;
       }

This patch leaves the issue with the locked page yet to be resolved.

Signed-off-by: Mitch Harder <mitch.harder@sabayonlinux.org>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-01-26 15:01:11 -05:00
Chris Mason
c126dea771 Merge branch 'integrity-check-patch-v2' of git://btrfs.giantdisaster.de/git/btrfs into integration
Conflicts:
	fs/btrfs/ctree.h
	fs/btrfs/super.c

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-01-16 15:27:58 -05:00
Chris Mason
9785dbdf26 Merge branch 'for-chris' of git://git.jan-o-sch.net/btrfs-unstable into integration 2012-01-16 15:26:31 -05:00
Arne Jansen
5b25f70f42 Btrfs: add nested locking mode for paths
This patch adds the possibilty to read-lock an extent even if it is already
write-locked from the same thread. btrfs_find_all_roots() needs this
capability.

Signed-off-by: Arne Jansen <sensille@gmx.net>
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
2012-01-04 16:12:29 +01:00
Stefan Behrens
21adbd5cbb Btrfs: integrate integrity check module into btrfs
This is the last part of the patch series. It modifies the btrfs
code to use the integrity check module if configured to do so
with the define BTRFS_FS_CHECK_INTEGRITY. If this define is not set,
the only effective change is that code is added that handles the
mount option to activate the integrity check. If the mount option is
set and the define BTRFS_FS_CHECK_INTEGRITY is not set, that code
complains in the log and the mount fails with EINVAL.

Add the mount option to activate the usage of the integrity check
code.
Add invocation of btrfs integrity check code init and cleanup
function on mount and umount, respectively.
Add hook to call btrfs integrity check code version of
submit_bh/submit_bio.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
2011-12-21 19:14:17 +01:00
Liu Bo
1cf4ffdb32 Btrfs: drop spin lock when memory alloc fails
Drop spin lock in convert_extent_bit() when memory alloc fails,
otherwise, it will be a deadlock.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-12-08 08:55:47 -05:00
Jan Schmidt
f4a8e6563e Btrfs: fix meta data raid-repair merge problem
Commit 4a54c8c16 introduced raid-repair, killing the individual
readpage_io_failed_hook entries from inode.c and disk-io.c. Commit
4bb31e92 introduced new readahead code, adding a readpage_io_failed_hook to
disk-io.c.

The raid-repair commit had logic to disable raid-repair, if
readpage_io_failed_hook is set. Thus, the readahead commit effectively
disabled raid-repair for meta data.

This commit changes the logic to always attempt raid-repair when needed and
call the readpage_io_failed_hook in case raid-repair fails. This is much
more straight forward and should have been like that from the beginning.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Reported-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-12-01 09:30:36 -05:00
Josef Bacik
4d479cf010 Btrfs: sectorsize align offsets in fiemap
We've been hitting BUG()'s in btrfs_cont_expand and btrfs_fallocate and anywhere
else that calls btrfs_get_extent while running xfstests 13 in a loop.  This is
because fiemap is calling btrfs_get_extent with non-sectorsize aligned offsets,
which will end up adding mappings that are not sectorsize aligned, which will
cause problems in some cases for subsequent calls to btrfs_get_extent for
similar areas that are sectorsize aligned.  With this patch I ran xfstests 13 in
a loop for a couple of hours and didn't hit the problem that I could previously
hit in at most 20 minutes.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2011-11-20 07:42:17 -05:00
Jan Schmidt
32240a913d btrfs: mirror_num should be int, not u64
My previous patch introduced some u64 for failed_mirror variables, this one
makes it consistent again.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-11-20 07:42:14 -05:00
Jeff Mahoney
745c4d8e16 btrfs: Fix up 32/64-bit compatibility for new ioctls
This patch casts to unsigned long before casting to a pointer and fixes
 the following warnings:
fs/btrfs/extent_io.c:2289:20: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
fs/btrfs/ioctl.c:2933:37: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
fs/btrfs/ioctl.c:2937:21: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
fs/btrfs/ioctl.c:3020:21: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
fs/btrfs/scrub.c:275:4: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
fs/btrfs/backref.c:686:27: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-11-20 07:42:13 -05:00
Chris Mason
806468f8bf Merge git://git.jan-o-sch.net/btrfs-unstable into integration
Conflicts:
	fs/btrfs/Makefile
	fs/btrfs/extent_io.c
	fs/btrfs/extent_io.h
	fs/btrfs/scrub.c

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-11-06 03:07:10 -05:00
Chris Mason
531f4b1ae5 Merge branch 'for-chris' of git://github.com/sensille/linux into integration
Conflicts:
	fs/btrfs/ctree.h

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-11-06 03:05:08 -05:00
Chris Mason
bf0da8c183 Btrfs: ClearPageError during writepage and clean_tree_block
Failure testing was tripping up over stale PageError bits in
metadata pages.  If we have an io error on a block, and later on
end up reusing it, nobody ever clears PageError on those pages.

During commit, we'll find PageError and think we had trouble writing
the block, which will lead to aborts and other problems.

This changes clean_tree_block and the btrfs writepage code to
clear the PageError bit.  In both cases we're either completely
done with the page or the page has good stuff and the error bit
is no longer valid.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-11-06 03:04:20 -05:00
Chris Mason
01d658f2ca Btrfs: make sure to flush queued bios if write_cache_pages waits
write_cache_pages tries to build up a large bio to stuff down the pipe.
But if it needs to wait for a page lock, it needs to make sure and send
down any pending writes so we don't deadlock with anyone who has the
page lock and is waiting for writeback of things inside the bio.

Dave Sterba triggered this as a deadlock between the autodefrag code and
the extent write_cache_pages

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-11-06 03:03:48 -05:00
Liu Bo
fee187d9d9 Btrfs: do not set EXTENT_DIRTY along with EXTENT_DELALLOC
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
2011-10-20 18:10:45 +02:00
Josef Bacik
462d6fac89 Btrfs: introduce convert_extent_bit
If I have a range where I know a certain bit is and I want to set it to another
bit the only option I have is to call set and then clear bit, which will result
in 2 tree searches.  This is inefficient, so introduce convert_extent_bit which
will go through and set the bit I want and clear the old bit I don't want.
Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2011-10-19 15:12:47 -04:00
Josef Bacik
9e4871070b Btrfs: skip looking for delalloc if we don't have ->fill_delalloc
We always look for delalloc bytes in our io_tree so we can fill in delalloc.
This is fine in most cases, but if we're writing out the btree_inode this is
just a superfluous tree search on the io_tree, and if we have a lot of metadata
dirty this could be an expensive check.  So instead check to see if our io_tree
has a ->fill_delalloc op, and if not don't even bother doing the lookup.
Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2011-10-19 15:12:30 -04:00
Arne Jansen
4bb31e928d btrfs: hooks for readahead
This adds the hooks needed for readahead. In the readpage_end_io_hook,
the extent state is checked for the EXTENT_READAHEAD flag. Only in this
case the readahead hook is called, to keep the impact on non-ra as low
as possible.
Additionally, a hook for a failed IO is added, otherwise readahead would
wait indefinitely for the extent to finish.

Changes for v2:
 - eliminate race condition

Signed-off-by: Arne Jansen <sensille@gmx.net>
2011-10-02 08:48:44 +02:00
Arne Jansen
bb82ab88df btrfs: add an extra wait mode to read_extent_buffer_pages
read_extent_buffer_pages currently has two modes, either trigger a read
without waiting for anything, or wait for the I/O to finish. The former
also bails when it's unable to lock the page. This patch now adds an
additional parameter to allow it to block on page lock, but don't wait
for completion.

Changes v5:
 - merge the 2 wait parameters into one and define WAIT_NONE, WAIT_COMPLETE and
   WAIT_PAGE_LOCK

Change v6:
 - fix bug introduced in v5

Signed-off-by: Arne Jansen <sensille@gmx.net>
2011-10-02 08:47:55 +02:00
Jan Schmidt
4a54c8c165 btrfs: Moved repair code from inode.c to extent_io.c
The raid-retry code in inode.c can be generalized so that it works for
metadata as well. Thus, this patch moves it to extent_io.c and makes the
raid-retry code a raid-repair code.

Repair works that way: Whenever a read error occurs and we have more
mirrors to try, note the failed mirror, and retry another. If we find a
good one, check if we did note a failure earlier and if so, do not allow
the read to complete until after the bad sector was written with the good
data we just fetched. As we have the extent locked while reading, no one
can change the data in between.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
2011-09-29 13:38:42 +02:00