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  1. 02 Oct, 2014 6 commits
  3. 23 Sep, 2014 3 commits
    • Josef Bacik's avatar
      Btrfs: try not to ENOSPC on log replay · 1d52c78a
      Josef Bacik authored 
      When doing log replay we may have to update inodes, which traditionally goes
through our delayed inode stuff.  This will try to move space over from the
trans handle, but we don't reserve space in our trans handle on replay since we
don't know how much we will need, so instead we try to flush.  But because we
have a trans handle open we won't flush anything, so if we are out of reserve
space we will simply return ENOSPC.  Since we know that if an operation made it
into the log then we definitely had space before the box bought the farm then we
don't need to worry about doing this space reservation.  Use the
fs_info->log_root_recovering flag to skip the delayed inode stuff and update the
item directly.  Thanks,
Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      1d52c78a
    • Josef Bacik's avatar
      Btrfs: don't do async reclaim during log replay · f6acfd50
      Josef Bacik authored 
      Trying to reproduce a log enospc bug I hit a panic in the async reclaim code
during log replay.  This is because we use fs_info->fs_root as our root for
shrinking and such.  Technically we can use whatever root we want, but let's
just not allow async reclaim while we're doing log replay.  Thanks,
Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      f6acfd50
    • Josef Bacik's avatar
      Btrfs: remove empty block groups automatically · 47ab2a6c
      Josef Bacik authored 
      One problem that has plagued us is that a user will use up all of his space with
data, remove a bunch of that data, and then try to create a bunch of small files
and run out of space.  This happens because all the chunks were allocated for
data since the metadata requirements were so low.  But now there's a bunch of
empty data block groups and not enough metadata space to do anything.  This
patch solves this problem by automatically deleting empty block groups.  If we
notice the used count go down to 0 when deleting or on mount notice that a block
group has a used count of 0 then we will queue it to be deleted.

When the cleaner thread runs we will double check to make sure the block group
is still empty and then we will delete it.  This patch has the side effect of no
longer having a bunch of BUG_ON()'s in the chunk delete code, which will be
helpful for both this and relocate.  Thanks,
Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      47ab2a6c
  5. 19 Sep, 2014 2 commits
    • Filipe Manana's avatar
      Btrfs: fix data corruption after fast fsync and writeback error · 8407f553
      Filipe Manana authored 
      When we do a fast fsync, we start all ordered operations and then while
they're running in parallel we visit the list of modified extent maps
and construct their matching file extent items and write them to the
log btree. After that, in btrfs_sync_log() we wait for all the ordered
operations to finish (via btrfs_wait_logged_extents).

The problem with this is that we were completely ignoring errors that
can happen in the extent write path, such as -ENOSPC, a temporary -ENOMEM
or -EIO errors for example. When such error happens, it means we have parts
of the on disk extent that weren't written to, and so we end up logging
file extent items that point to these extents that contain garbage/random
data - so after a crash/reboot plus log replay, we get our inode's metadata
pointing to those extents.

This worked in contrast with the full (non-fast) fsync path, where we
start all ordered operations, wait for them to finish and then write
to the log btree. In this path, after each ordered operation completes
we check if it's flagged with an error (BTRFS_ORDERED_IOERR) and return
-EIO if so (via btrfs_wait_ordered_range).

So if an error happens with any ordered operation, just return a -EIO
error to userspace, so that it knows that not all of its previous writes
were durably persisted and the application can take proper action (like
redo the writes for e.g.) - and definitely not leave any file extent items
in the log refer to non fully written extents.
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      8407f553
    • Filipe Manana's avatar
      Btrfs: fix fsync race leading to invalid data after log replay · 669249ee
      Filipe Manana authored 
      When the fsync callback (btrfs_sync_file) starts, it first waits for
the writeback of any dirty pages to start and finish without holding
the inode's mutex (to reduce contention). After this it acquires the
inode's mutex and repeats that process via btrfs_wait_ordered_range
only if we're doing a full sync (BTRFS_INODE_NEEDS_FULL_SYNC flag
is set on the inode).

This is not safe for a non full sync - we need to start and wait for
writeback to finish for any pages that might have been made dirty
before acquiring the inode's mutex and after that first step mentioned
before. Why this is needed is explained by the following comment added
to btrfs_sync_file:

  "Right before acquiring the inode's mutex, we might have new
   writes dirtying pages, which won't immediately start the
   respective ordered operations - that is done through the
   fill_delalloc callbacks invoked from the writepage and
   writepages address space operations. So make sure we start
   all ordered operations before starting to log our inode. Not
   doing this means that while logging the inode, writeback
   could start and invoke writepage/writepages, which would call
   the fill_delalloc callbacks (cow_file_range,
   submit_compressed_extents). These callbacks add first an
   extent map to the modified list of extents and then create
   the respective ordered operation, which means in
   tree-log.c:btrfs_log_inode() we might capture all existing
   ordered operations (with btrfs_get_logged_extents()) before
   the fill_delalloc callback adds its ordered operation, and by
   the time we visit the modified list of extent maps (with
   btrfs_log_changed_extents()), we see and process the extent
   map they created. We then use the extent map to construct a
   file extent item for logging without waiting for the
   respective ordered operation to finish - this file extent
   item points to a disk location that might not have yet been
   written to, containing random data - so after a crash a log
   replay will make our inode have file extent items that point
   to disk locations containing invalid data, as we returned
   success to userspace without waiting for the respective
   ordered operation to finish, because it wasn't captured by
   btrfs_get_logged_extents()."
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      669249ee
  7. 18 Sep, 2014 2 commits
    • Liu Bo's avatar
      Btrfs: fix wrong parse of extent map's tracepoint · 254a2d14
      Liu Bo authored 
      The tracepoint of extent map doesn't parse @flag correctly, we set @flag via
set_bit(), so we need to parse it on a bit bias.

Also add the missing flag, EXTENT_FLAG_FS_MAPPING.
Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      254a2d14
    • Qu Wenruo's avatar
      btrfs: Fix and enhance merge_extent_mapping() to insert best fitted extent map · e6c4efd8
      Qu Wenruo authored 
      The following commit enhanced the merge_extent_mapping() to reduce
fragment in extent map tree, but it can't handle case which existing
lies before map_start:
51f39 btrfs: Use right extent length when inserting overlap extent map.

[BUG]
When existing extent map's start is before map_start,
the em->len will be minus, which will corrupt the extent map and fail to
insert the new extent map.
This will happen when someone get a large extent map, but when it is
going to insert it into extent map tree, some one has already commit
some write and split the huge extent into small parts.

[REPRODUCER]
It is very easy to tiger using filebench with randomrw personality.
It is about 100% to reproduce when using 8G preallocated file in 60s
randonrw test.

[FIX]
This patch can now handle any existing extent position.
Since it does not directly use existing->start, now it will find the
previous and next extent around map_start.
So the old existing->start < map_start bug will never happen again.

[ENHANCE]
This patch will insert the best fitted extent map into extent map tree,
other than the oldest [map_start, map_start + sectorsize) or the
relatively newer but not perfect [map_start, existing->start).

The patch will first search existing extent that does not intersects with
the desired map range [map_start, map_start + len).
The existing extent will be either before or behind map_start, and based
on the existing extent, we can find out the previous and next extent
around map_start.

So the best fitted extent would be [prev->end, next->start).
For prev or next is not found, em->start would be prev->end and em->end
wold be next->start.

With this patch, the fragment in extent map tree should be reduced much
more than the 51f39 commit and reduce an unneeded extent map tree search.
Reported-by: default avatarTsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: default avatarQu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
      e6c4efd8
  9. 17 Sep, 2014 27 commits
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