diff options
| author | Christoph Hellwig <hch@lst.de> | 2016-09-19 11:24:50 +1000 |
|---|---|---|
| committer | Dave Chinner <david@fromorbit.com> | 2016-09-19 11:24:50 +1000 |
| commit | 17879e8f865f4ed8b6f9041a2687ad40f13ae460 (patch) | |
| tree | 4d543b880fb8d762b4a57a4988a2099c1115428b /fs | |
| parent | a7d73fe6c538fdba42635c0b8e73382fcd4bd667 (diff) | |
xfs: fix locking for DAX writes
So far DAX writes inherited the locking from direct I/O writes, but
the direct I/O model of using shared locks for writes is actually
wrong for DAX. For direct I/O we're out of any standards and don't
have to provide the Posix required exclusion between writers, but
for DAX which gets transparently enable on applications without any
knowledge of it we can't simply drop the requirement. Even worse
this only happens for aligned writes and thus doesn't show up for
many typical use cases.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/xfs/xfs_file.c | 20 |
1 files changed, 1 insertions, 19 deletions
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index e612a0233710..62649ccdbb4d 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -714,24 +714,11 @@ xfs_file_dax_write( struct address_space *mapping = iocb->ki_filp->f_mapping; struct inode *inode = mapping->host; struct xfs_inode *ip = XFS_I(inode); - struct xfs_mount *mp = ip->i_mount; ssize_t ret = 0; - int unaligned_io = 0; - int iolock; + int iolock = XFS_IOLOCK_EXCL; struct iov_iter data; - /* "unaligned" here means not aligned to a filesystem block */ - if ((iocb->ki_pos & mp->m_blockmask) || - ((iocb->ki_pos + iov_iter_count(from)) & mp->m_blockmask)) { - unaligned_io = 1; - iolock = XFS_IOLOCK_EXCL; - } else if (mapping->nrpages) { - iolock = XFS_IOLOCK_EXCL; - } else { - iolock = XFS_IOLOCK_SHARED; - } xfs_rw_ilock(ip, iolock); - ret = xfs_file_aio_write_checks(iocb, from, &iolock); if (ret) goto out; @@ -758,11 +745,6 @@ xfs_file_dax_write( WARN_ON_ONCE(ret); } - if (iolock == XFS_IOLOCK_EXCL && !unaligned_io) { - xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL); - iolock = XFS_IOLOCK_SHARED; - } - trace_xfs_file_dax_write(ip, iov_iter_count(from), iocb->ki_pos); data = *from; |