| Message ID | 1491494876-14433-1-git-send-email-fdmanana@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Apr 06, 2017 at 05:07:56PM +0100, fdmanana@kernel.org wrote: > From: Filipe Manana <fdmanana@suse.com> > > Normally we don't have inline extents followed by regular extents, but > there's currently at least one harmless case where this happens. For > example, when the page size is 4Kb and compression is enabled: > > $ mkfs.btrfs -f /dev/sdb > $ mount -o compress /dev/sdb /mnt > $ xfs_io -f -c "pwrite -S 0xaa 0 4K" -c "fsync" /mnt/foobar > $ xfs_io -c "pwrite -S 0xbb 8K 4K" -c "fsync" /mnt/foobar > > In this case we get a compressed inline extent, representing 4Kb of > data, followed by a hole extent and then a regular data extent. The > inline extent was not expanded/converted to a regular extent exactly > because it represents 4Kb of data. This does not cause any apparent > problem (such as the issue solved by commit e1699d2d7bf6 > ("btrfs: add missing memset while reading compressed inline extents")) > except trigger an unexpected case in the incremental send code path > that makes us issue an operation to write a hole when it's not needed, > resulting in more writes at the receiver and wasting space at the > receiver. > > So teach the incremental send code to deal with this particular case. > > The issue can be currently triggered by running fstests btrfs/137 with > compression enabled (MOUNT_OPTIONS="-o compress" ./check btrfs/137). > Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Thanks, -liubo > Signed-off-by: Filipe Manana <fdmanana@suse.com> > --- > fs/btrfs/send.c | 23 +++++++++++++++++++++-- > 1 file changed, 21 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c > index 456c890..f66095a 100644 > --- a/fs/btrfs/send.c > +++ b/fs/btrfs/send.c > @@ -5184,13 +5184,19 @@ static int is_extent_unchanged(struct send_ctx *sctx, > while (key.offset < ekey->offset + left_len) { > ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); > right_type = btrfs_file_extent_type(eb, ei); > - if (right_type != BTRFS_FILE_EXTENT_REG) { > + if (right_type != BTRFS_FILE_EXTENT_REG && > + right_type != BTRFS_FILE_EXTENT_INLINE) { > ret = 0; > goto out; > } > > right_disknr = btrfs_file_extent_disk_bytenr(eb, ei); > - right_len = btrfs_file_extent_num_bytes(eb, ei); > + if (right_type == BTRFS_FILE_EXTENT_INLINE) { > + right_len = btrfs_file_extent_inline_len(eb, slot, ei); > + right_len = PAGE_ALIGN(right_len); > + } else { > + right_len = btrfs_file_extent_num_bytes(eb, ei); > + } > right_offset = btrfs_file_extent_offset(eb, ei); > right_gen = btrfs_file_extent_generation(eb, ei); > > @@ -5204,6 +5210,19 @@ static int is_extent_unchanged(struct send_ctx *sctx, > goto out; > } > > + /* > + * We just wanted to see if when we have an inline extent, what > + * follows it is a regular extent (wanted to check the above > + * condition for inline extents too). This should normally not > + * happen but it's possible for example when we have an inline > + * compressed extent representing data with a size matching > + * the page size (currently the same as sector size). > + */ > + if (right_type == BTRFS_FILE_EXTENT_INLINE) { > + ret = 0; > + goto out; > + } > + > left_offset_fixed = left_offset; > if (key.offset < ekey->offset) { > /* Fix the right offset for 2a and 7. */ > -- > 2.7.0.rc3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 456c890..f66095a 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -5184,13 +5184,19 @@ static int is_extent_unchanged(struct send_ctx *sctx, while (key.offset < ekey->offset + left_len) { ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); right_type = btrfs_file_extent_type(eb, ei); - if (right_type != BTRFS_FILE_EXTENT_REG) { + if (right_type != BTRFS_FILE_EXTENT_REG && + right_type != BTRFS_FILE_EXTENT_INLINE) { ret = 0; goto out; } right_disknr = btrfs_file_extent_disk_bytenr(eb, ei); - right_len = btrfs_file_extent_num_bytes(eb, ei); + if (right_type == BTRFS_FILE_EXTENT_INLINE) { + right_len = btrfs_file_extent_inline_len(eb, slot, ei); + right_len = PAGE_ALIGN(right_len); + } else { + right_len = btrfs_file_extent_num_bytes(eb, ei); + } right_offset = btrfs_file_extent_offset(eb, ei); right_gen = btrfs_file_extent_generation(eb, ei); @@ -5204,6 +5210,19 @@ static int is_extent_unchanged(struct send_ctx *sctx, goto out; } + /* + * We just wanted to see if when we have an inline extent, what + * follows it is a regular extent (wanted to check the above + * condition for inline extents too). This should normally not + * happen but it's possible for example when we have an inline + * compressed extent representing data with a size matching + * the page size (currently the same as sector size). + */ + if (right_type == BTRFS_FILE_EXTENT_INLINE) { + ret = 0; + goto out; + } + left_offset_fixed = left_offset; if (key.offset < ekey->offset) { /* Fix the right offset for 2a and 7. */