diff options
author | Christoph Hellwig <hch@lst.de> | 2019-02-18 18:38:48 +0100 |
---|---|---|
committer | Darrick J. Wong <darrick.wong@oracle.com> | 2019-02-21 16:55:07 +0100 |
commit | 26b91c728b2d15952432371dc2b6ba1dda1fb61f (patch) | |
tree | a666a88de0bbe438c2e7371910f5f63d1d54cece /fs/xfs/xfs_reflink.c | |
parent | xfs: merge COW handling into xfs_file_iomap_begin_delay (diff) | |
download | linux-26b91c728b2d15952432371dc2b6ba1dda1fb61f.tar.xz linux-26b91c728b2d15952432371dc2b6ba1dda1fb61f.zip |
xfs: make COW fork unwritten extent conversions more robust
If we have racing buffered and direct I/O COW fork extents under
writeback can have been moved to the data fork by the time we call
xfs_reflink_convert_cow from xfs_submit_ioend. This would be mostly
harmless as the block numbers don't change by this move, except for
the fact that xfs_bmapi_write will crash or trigger asserts when
not finding existing extents, even despite trying to paper over this
with the XFS_BMAPI_CONVERT_ONLY flag.
Instead of special casing non-transaction conversions in the already
way too complicated xfs_bmapi_write just add a new helper for the much
simpler non-transactional COW fork case, which simplify ignores not
found extents.
Signed-off-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>
Diffstat (limited to '')
-rw-r--r-- | fs/xfs/xfs_reflink.c | 61 |
1 files changed, 38 insertions, 23 deletions
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 9ef1f79cb3ae..f84b37fa4f17 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -234,26 +234,42 @@ xfs_reflink_trim_around_shared( } } -/* Convert part of an unwritten CoW extent to a real one. */ -STATIC int -xfs_reflink_convert_cow_extent( - struct xfs_inode *ip, - struct xfs_bmbt_irec *imap, - xfs_fileoff_t offset_fsb, - xfs_filblks_t count_fsb) +static int +xfs_reflink_convert_cow_locked( + struct xfs_inode *ip, + xfs_fileoff_t offset_fsb, + xfs_filblks_t count_fsb) { - int nimaps = 1; + struct xfs_iext_cursor icur; + struct xfs_bmbt_irec got; + struct xfs_btree_cur *dummy_cur = NULL; + int dummy_logflags; + int error; - if (imap->br_state == XFS_EXT_NORM) + if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got)) return 0; - xfs_trim_extent(imap, offset_fsb, count_fsb); - trace_xfs_reflink_convert_cow(ip, imap); - if (imap->br_blockcount == 0) - return 0; - return xfs_bmapi_write(NULL, ip, imap->br_startoff, imap->br_blockcount, - XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT, 0, imap, - &nimaps); + do { + if (got.br_startoff >= offset_fsb + count_fsb) + break; + if (got.br_state == XFS_EXT_NORM) + continue; + if (WARN_ON_ONCE(isnullstartblock(got.br_startblock))) + return -EIO; + + xfs_trim_extent(&got, offset_fsb, count_fsb); + if (!got.br_blockcount) + continue; + + got.br_state = XFS_EXT_NORM; + error = xfs_bmap_add_extent_unwritten_real(NULL, ip, + XFS_COW_FORK, &icur, &dummy_cur, &got, + &dummy_logflags); + if (error) + return error; + } while (xfs_iext_next_extent(ip->i_cowfp, &icur, &got)); + + return error; } /* Convert all of the unwritten CoW extents in a file's range to real ones. */ @@ -267,15 +283,12 @@ xfs_reflink_convert_cow( xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset); xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count); xfs_filblks_t count_fsb = end_fsb - offset_fsb; - struct xfs_bmbt_irec imap; - int nimaps = 1, error = 0; + int error; ASSERT(count != 0); xfs_ilock(ip, XFS_ILOCK_EXCL); - error = xfs_bmapi_write(NULL, ip, offset_fsb, count_fsb, - XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT | - XFS_BMAPI_CONVERT_ONLY, 0, &imap, &nimaps); + error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb); xfs_iunlock(ip, XFS_ILOCK_EXCL); return error; } @@ -405,14 +418,16 @@ xfs_reflink_allocate_cow( if (nimaps == 0) return -ENOSPC; convert: + xfs_trim_extent(imap, offset_fsb, count_fsb); /* * COW fork extents are supposed to remain unwritten until we're ready * to initiate a disk write. For direct I/O we are going to write the * data and need the conversion, but for buffered writes we're done. */ - if (!(iomap_flags & IOMAP_DIRECT)) + if (!(iomap_flags & IOMAP_DIRECT) || imap->br_state == XFS_EXT_NORM) return 0; - return xfs_reflink_convert_cow_extent(ip, imap, offset_fsb, count_fsb); + trace_xfs_reflink_convert_cow(ip, imap); + return xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb); out_unreserve: xfs_trans_unreserve_quota_nblks(tp, ip, (long)resblks, 0, |