Commit 66642c5c authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Dave Chinner

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: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent 17879e8f
...@@ -954,6 +954,7 @@ xfs_file_iomap_begin( ...@@ -954,6 +954,7 @@ xfs_file_iomap_begin(
struct xfs_bmbt_irec imap; struct xfs_bmbt_irec imap;
xfs_fileoff_t offset_fsb, end_fsb; xfs_fileoff_t offset_fsb, end_fsb;
int nimaps = 1, error = 0; int nimaps = 1, error = 0;
unsigned lockmode;
if (XFS_FORCED_SHUTDOWN(mp)) if (XFS_FORCED_SHUTDOWN(mp))
return -EIO; return -EIO;
...@@ -963,7 +964,7 @@ xfs_file_iomap_begin( ...@@ -963,7 +964,7 @@ xfs_file_iomap_begin(
iomap); iomap);
} }
xfs_ilock(ip, XFS_ILOCK_EXCL); lockmode = xfs_ilock_data_map_shared(ip);
ASSERT(offset <= mp->m_super->s_maxbytes); ASSERT(offset <= mp->m_super->s_maxbytes);
if ((xfs_fsize_t)offset + length > mp->m_super->s_maxbytes) if ((xfs_fsize_t)offset + length > mp->m_super->s_maxbytes)
...@@ -974,7 +975,7 @@ xfs_file_iomap_begin( ...@@ -974,7 +975,7 @@ xfs_file_iomap_begin(
error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap, error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
&nimaps, XFS_BMAPI_ENTIRE); &nimaps, XFS_BMAPI_ENTIRE);
if (error) { if (error) {
xfs_iunlock(ip, XFS_ILOCK_EXCL); xfs_iunlock(ip, lockmode);
return error; return error;
} }
...@@ -994,7 +995,8 @@ xfs_file_iomap_begin( ...@@ -994,7 +995,8 @@ xfs_file_iomap_begin(
* xfs_iomap_write_direct() expects the shared lock. It * xfs_iomap_write_direct() expects the shared lock. It
* is unlocked on return. * 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, error = xfs_iomap_write_direct(ip, offset, length, &imap,
nimaps); nimaps);
if (error) if (error)
...@@ -1005,7 +1007,7 @@ xfs_file_iomap_begin( ...@@ -1005,7 +1007,7 @@ xfs_file_iomap_begin(
} else { } else {
ASSERT(nimaps); ASSERT(nimaps);
xfs_iunlock(ip, XFS_ILOCK_EXCL); xfs_iunlock(ip, lockmode);
trace_xfs_iomap_found(ip, offset, length, 0, &imap); trace_xfs_iomap_found(ip, offset, length, 0, &imap);
} }
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment