xfs: fix AIM7 regression

Apparently our current rwsem code doesn't like doing the trylock, then
lock for real scheme.  So change our read/write methods to just do the
trylock for the RWF_NOWAIT case.  This fixes a ~25% regression in
AIM7.

Fixes: 91f9943e ("fs: support RWF_NOWAIT for buffered reads")
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 56d0e526870c61970939373fabaddaeecfa0253c..6526ef0e2a234965e7895e823b544f24faedb81a 100644 (file)
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -237,11 +237,13 @@ xfs_file_dax_read(
        if (!count)
                return 0; /* skip atime */
 
-       if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED)) {
-               if (iocb->ki_flags & IOCB_NOWAIT)
+       if (iocb->ki_flags & IOCB_NOWAIT) {
+               if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED))
                        return -EAGAIN;
+       } else {
                xfs_ilock(ip, XFS_IOLOCK_SHARED);
        }
+
        ret = dax_iomap_rw(iocb, to, &xfs_iomap_ops);
        xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 
@@ -259,9 +261,10 @@ xfs_file_buffered_aio_read(
 
        trace_xfs_file_buffered_read(ip, iov_iter_count(to), iocb->ki_pos);
 
-       if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED)) {
-               if (iocb->ki_flags & IOCB_NOWAIT)
+       if (iocb->ki_flags & IOCB_NOWAIT) {
+               if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED))
                        return -EAGAIN;
+       } else {
                xfs_ilock(ip, XFS_IOLOCK_SHARED);
        }
        ret = generic_file_read_iter(iocb, to);
@@ -552,9 +555,10 @@ xfs_file_dio_aio_write(
                iolock = XFS_IOLOCK_SHARED;
        }
 
-       if (!xfs_ilock_nowait(ip, iolock)) {
-               if (iocb->ki_flags & IOCB_NOWAIT)
+       if (iocb->ki_flags & IOCB_NOWAIT) {
+               if (!xfs_ilock_nowait(ip, iolock))
                        return -EAGAIN;
+       } else {
                xfs_ilock(ip, iolock);
        }
 
@@ -606,9 +610,10 @@ xfs_file_dax_write(
        size_t                  count;
        loff_t                  pos;
 
-       if (!xfs_ilock_nowait(ip, iolock)) {
-               if (iocb->ki_flags & IOCB_NOWAIT)
+       if (iocb->ki_flags & IOCB_NOWAIT) {
+               if (!xfs_ilock_nowait(ip, iolock))
                        return -EAGAIN;
+       } else {
                xfs_ilock(ip, iolock);
        }