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authorChristoph Hellwig <hch@lst.de>2019-02-18 18:38:48 +0100
committerDarrick J. Wong <darrick.wong@oracle.com>2019-02-21 16:55:07 +0100
commit26b91c728b2d15952432371dc2b6ba1dda1fb61f (patch)
treea666a88de0bbe438c2e7371910f5f63d1d54cece /fs/xfs/xfs_reflink.c
parentxfs: merge COW handling into xfs_file_iomap_begin_delay (diff)
downloadlinux-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.c61
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,