| Message ID | 20210126063232.3648053-6-chandanrlinux@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | Bail out if transaction can cause extent count to overflow | expand |
On 1/25/21 11:32 PM, Chandan Babu R wrote: > Directory entry removal must always succeed; Hence XFS does the > following during low disk space scenario: > 1. Data/Free blocks linger until a future remove operation. > 2. Dabtree blocks would be swapped with the last block in the leaf space > and then the new last block will be unmapped. > > This facility is reused during low inode extent count scenario i.e. this > commit causes xfs_bmap_del_extent_real() to return -ENOSPC error code so > that the above mentioned behaviour is exercised causing no change to the > directory's extent count. > > Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> > Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com> Ok, makes sense. Thanks for the commentary! Reviewed-by: Allison Henderson <allison.henderson@oracle.com> > --- > fs/xfs/libxfs/xfs_bmap.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c > index 32aeacf6f055..6c8f17a0e247 100644 > --- a/fs/xfs/libxfs/xfs_bmap.c > +++ b/fs/xfs/libxfs/xfs_bmap.c > @@ -5151,6 +5151,24 @@ xfs_bmap_del_extent_real( > /* > * Deleting the middle of the extent. > */ > + > + /* > + * For directories, -ENOSPC is returned since a directory entry > + * remove operation must not fail due to low extent count > + * availability. -ENOSPC will be handled by higher layers of XFS > + * by letting the corresponding empty Data/Free blocks to linger > + * until a future remove operation. Dabtree blocks would be > + * swapped with the last block in the leaf space and then the > + * new last block will be unmapped. > + */ > + error = xfs_iext_count_may_overflow(ip, whichfork, 1); > + if (error) { > + ASSERT(S_ISDIR(VFS_I(ip)->i_mode) && > + whichfork == XFS_DATA_FORK); > + error = -ENOSPC; > + goto done; > + } > + > old = got; > > got.br_blockcount = del->br_startoff - got.br_startoff; >
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 32aeacf6f055..6c8f17a0e247 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -5151,6 +5151,24 @@ xfs_bmap_del_extent_real( /* * Deleting the middle of the extent. */ + + /* + * For directories, -ENOSPC is returned since a directory entry + * remove operation must not fail due to low extent count + * availability. -ENOSPC will be handled by higher layers of XFS + * by letting the corresponding empty Data/Free blocks to linger + * until a future remove operation. Dabtree blocks would be + * swapped with the last block in the leaf space and then the + * new last block will be unmapped. + */ + error = xfs_iext_count_may_overflow(ip, whichfork, 1); + if (error) { + ASSERT(S_ISDIR(VFS_I(ip)->i_mode) && + whichfork == XFS_DATA_FORK); + error = -ENOSPC; + goto done; + } + old = got; got.br_blockcount = del->br_startoff - got.br_startoff;