From: Brian Foster bfoster@redhat.com
commit 211683b21de959a647de74faedfdd8a5d189327e upstream.
The collapse range operation uses a unique transaction and ilock cycle for the hole punch and each extent shift iteration of the overall operation. While the hole punch is safe as a separate operation due to the iolock, cycling the ilock after each extent shift is risky w.r.t. concurrent operations, similar to insert range.
To avoid this problem, make collapse range atomic with respect to ilock. Hold the ilock across the entire operation, replace the individual transactions with a single rolling transaction sequence and finish dfops on each iteration to perform pending frees and roll the transaction. Remove the unnecessary quota reservation as collapse range can only ever merge extents (and thus remove extent records and potentially free bmap blocks). The dfops call automatically relogs the inode to keep it moving in the log. This guarantees that nothing else can change the extent mapping of an inode while a collapse range operation is in progress.
Signed-off-by: Brian Foster bfoster@redhat.com Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Darrick J. Wong darrick.wong@oracle.com Signed-off-by: Darrick J. Wong darrick.wong@oracle.com Acked-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Chandan Babu R chandan.babu@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/xfs/xfs_bmap_util.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-)
--- a/fs/xfs/xfs_bmap_util.c +++ b/fs/xfs/xfs_bmap_util.c @@ -1237,7 +1237,6 @@ xfs_collapse_file_space( int error; xfs_fileoff_t next_fsb = XFS_B_TO_FSB(mp, offset + len); xfs_fileoff_t shift_fsb = XFS_B_TO_FSB(mp, len); - uint resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0); bool done = false;
ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL)); @@ -1253,32 +1252,34 @@ xfs_collapse_file_space( if (error) return error;
- while (!error && !done) { - error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, - &tp); - if (error) - break; + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp); + if (error) + return error;
- xfs_ilock(ip, XFS_ILOCK_EXCL); - error = xfs_trans_reserve_quota(tp, mp, ip->i_udquot, - ip->i_gdquot, ip->i_pdquot, resblks, 0, - XFS_QMOPT_RES_REGBLKS); - if (error) - goto out_trans_cancel; - xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL); + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, ip, 0);
+ while (!done) { error = xfs_bmap_collapse_extents(tp, ip, &next_fsb, shift_fsb, &done); if (error) goto out_trans_cancel; + if (done) + break;
- error = xfs_trans_commit(tp); + /* finish any deferred frees and roll the transaction */ + error = xfs_defer_finish(&tp); + if (error) + goto out_trans_cancel; }
+ error = xfs_trans_commit(tp); + xfs_iunlock(ip, XFS_ILOCK_EXCL); return error;
out_trans_cancel: xfs_trans_cancel(tp); + xfs_iunlock(ip, XFS_ILOCK_EXCL); return error; }