xfs: remove nonblocking mode from xfs_vm_writepage

Remove the nonblocking optimisation done for mapping lookups during
writeback. It's not clear that leaving a hole in the writeback range
just because we couldn't get a lock is really a win, as it makes us
do another small random IO later on rather than a large sequential
IO now.

As this gets in the way of sane error handling later on, just remove
for the moment and we can re-introduce an equivalent optimisation in
future if we see problems due to extent map lock contention.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 379c089..807744b 100644 (file)
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -283,8 +283,7 @@ xfs_map_blocks(
        struct inode            *inode,
        loff_t                  offset,
        struct xfs_bmbt_irec    *imap,
-       int                     type,
-       int                     nonblocking)
+       int                     type)
 {
        struct xfs_inode        *ip = XFS_I(inode);
        struct xfs_mount        *mp = ip->i_mount;
@@ -300,12 +299,7 @@ xfs_map_blocks(
        if (type == XFS_IO_UNWRITTEN)
                bmapi_flags |= XFS_BMAPI_IGSTATE;
 
-       if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED)) {
-               if (nonblocking)
-                       return -EAGAIN;
-               xfs_ilock(ip, XFS_ILOCK_SHARED);
-       }
-
+       xfs_ilock(ip, XFS_ILOCK_SHARED);
        ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
               (ip->i_df.if_flags & XFS_IFEXTENTS));
        ASSERT(offset <= mp->m_super->s_maxbytes);
@@ -955,7 +949,6 @@ xfs_vm_writepage(
        ssize_t                 len;
        int                     err, imap_valid = 0, uptodate = 1;
        int                     count = 0;
-       int                     nonblocking = 0;
 
        trace_xfs_writepage(inode, page, 0, 0);
 
@@ -1055,9 +1048,6 @@ xfs_vm_writepage(
        offset = page_offset(page);
        type = XFS_IO_OVERWRITE;
 
-       if (wbc->sync_mode == WB_SYNC_NONE)
-               nonblocking = 1;
-
        do {
                int new_ioend = 0;
 
@@ -1117,8 +1107,7 @@ xfs_vm_writepage(
                         * time.
                         */
                        new_ioend = 1;
-                       err = xfs_map_blocks(inode, offset, &imap, type,
-                                            nonblocking);
+                       err = xfs_map_blocks(inode, offset, &imap, type);
                        if (err)
                                goto error;
                        imap_valid = xfs_imap_valid(inode, &imap, offset);
@@ -1188,9 +1177,6 @@ error:
        if (iohead)
                xfs_cancel_ioend(iohead);
 
-       if (err == -EAGAIN)
-               goto redirty;
-
        xfs_aops_discard_page(page);
        ClearPageUptodate(page);
        unlock_page(page);