diff options
author | Eryu Guan <eguan@redhat.com> | 2017-09-21 11:26:18 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-10-27 10:38:09 +0200 |
commit | 0eebfedec1449f31c2321723acdd3c36dcac7f0a (patch) | |
tree | 90e8fd86dbf11c6049ac301d80534a80f2f8b61e /fs/xfs/xfs_aops.c | |
parent | d1b2a35f8f5768beaa225621fcef6f07bf08a6ba (diff) |
xfs: update i_size after unwritten conversion in dio completion
commit ee70daaba82d70766d0723b743d9fdeb3b06102a upstream.
Since commit d531d91d6990 ("xfs: always use unwritten extents for
direct I/O writes"), we start allocating unwritten extents for all
direct writes to allow appending aio in XFS.
But for dio writes that could extend file size we update the in-core
inode size first, then convert the unwritten extents to real
allocations at dio completion time in xfs_dio_write_end_io(). Thus a
racing direct read could see the new i_size and find the unwritten
extents first and read zeros instead of actual data, if the direct
writer also takes a shared iolock.
Fix it by updating the in-core inode size after the unwritten extent
conversion. To do this, introduce a new boolean argument to
xfs_iomap_write_unwritten() to tell if we want to update in-core
i_size or not.
Suggested-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
[hch: backported to the old direct I/O code before Linux 4.10]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/xfs/xfs_aops.c')
-rw-r--r-- | fs/xfs/xfs_aops.c | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index d23889e0bedc..2b9d7c5800ee 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -335,7 +335,8 @@ xfs_end_io( error = xfs_reflink_end_cow(ip, offset, size); break; case XFS_IO_UNWRITTEN: - error = xfs_iomap_write_unwritten(ip, offset, size); + /* writeback should never update isize */ + error = xfs_iomap_write_unwritten(ip, offset, size, false); break; default: ASSERT(!xfs_ioend_is_append(ioend) || ioend->io_append_trans); @@ -1532,6 +1533,21 @@ xfs_end_io_direct_write( return 0; } + if (flags & XFS_DIO_FLAG_COW) + error = xfs_reflink_end_cow(ip, offset, size); + + /* + * Unwritten conversion updates the in-core isize after extent + * conversion but before updating the on-disk size. Updating isize any + * earlier allows a racing dio read to find unwritten extents before + * they are converted. + */ + if (flags & XFS_DIO_FLAG_UNWRITTEN) { + trace_xfs_end_io_direct_write_unwritten(ip, offset, size); + + return xfs_iomap_write_unwritten(ip, offset, size, true); + } + /* * We need to update the in-core inode size here so that we don't end up * with the on-disk inode size being outside the in-core inode size. We @@ -1548,13 +1564,6 @@ xfs_end_io_direct_write( i_size_write(inode, offset + size); spin_unlock(&ip->i_flags_lock); - if (flags & XFS_DIO_FLAG_COW) - error = xfs_reflink_end_cow(ip, offset, size); - if (flags & XFS_DIO_FLAG_UNWRITTEN) { - trace_xfs_end_io_direct_write_unwritten(ip, offset, size); - - error = xfs_iomap_write_unwritten(ip, offset, size); - } if (flags & XFS_DIO_FLAG_APPEND) { trace_xfs_end_io_direct_write_append(ip, offset, size); |