diff options
| author | Christoph Hellwig <hch@lst.de> | 2016-09-19 11:26:39 +1000 |
|---|---|---|
| committer | Dave Chinner <david@fromorbit.com> | 2016-09-19 11:26:39 +1000 |
| commit | 66642c5c1dea411dd2842159f9f297ce8e914994 (patch) | |
| tree | 693c729488f40154f7fd6878afc9897209ec82cd /fs/xfs/xfs_iomap.c | |
| parent | 17879e8f865f4ed8b6f9041a2687ad40f13ae460 (diff) | |
xfs: take the ilock shared if possible in xfs_file_iomap_begin
We always just read the extent first, and will later lock exlusively
after first dropping the lock in case we actually allocate blocks.
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/xfs/xfs_iomap.c')
| -rw-r--r-- | fs/xfs/xfs_iomap.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index ac677d032e3a..fe4a26d752d0 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -954,6 +954,7 @@ xfs_file_iomap_begin( struct xfs_bmbt_irec imap; xfs_fileoff_t offset_fsb, end_fsb; int nimaps = 1, error = 0; + unsigned lockmode; if (XFS_FORCED_SHUTDOWN(mp)) return -EIO; @@ -963,7 +964,7 @@ xfs_file_iomap_begin( iomap); } - xfs_ilock(ip, XFS_ILOCK_EXCL); + lockmode = xfs_ilock_data_map_shared(ip); ASSERT(offset <= mp->m_super->s_maxbytes); if ((xfs_fsize_t)offset + length > mp->m_super->s_maxbytes) @@ -974,7 +975,7 @@ xfs_file_iomap_begin( error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap, &nimaps, XFS_BMAPI_ENTIRE); if (error) { - xfs_iunlock(ip, XFS_ILOCK_EXCL); + xfs_iunlock(ip, lockmode); return error; } @@ -994,7 +995,8 @@ xfs_file_iomap_begin( * xfs_iomap_write_direct() expects the shared lock. It * is unlocked on return. */ - xfs_ilock_demote(ip, XFS_ILOCK_EXCL); + if (lockmode == XFS_ILOCK_EXCL) + xfs_ilock_demote(ip, lockmode); error = xfs_iomap_write_direct(ip, offset, length, &imap, nimaps); if (error) @@ -1005,7 +1007,7 @@ xfs_file_iomap_begin( } else { ASSERT(nimaps); - xfs_iunlock(ip, XFS_ILOCK_EXCL); + xfs_iunlock(ip, lockmode); trace_xfs_iomap_found(ip, offset, length, 0, &imap); } |