xfs: kill XBF_FS_MANAGED buffers

Filesystem level managed buffers are buffers that have their
lifecycle controlled by the filesystem layer, not the buffer cache.
We currently cache these buffers, which makes cleanup and cache
walking somewhat troublesome. Convert the fs managed buffers to
uncached buffers obtained by via xfs_buf_get_uncached(), and remove
the XBF_FS_MANAGED special cases from the buffer cache.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>

1 files changed, 16 insertions, 39 deletions

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 14fc6e9e1816..fbca293326e5 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -646,7 +646,6 @@ int
 xfs_readsb(xfs_mount_t *mp, int flags)
 {
         unsigned int    sector_size;
-        unsigned int    extra_flags;
         xfs_buf_t       *bp;
         int             error;
 
@@ -659,28 +658,24 @@ xfs_readsb(xfs_mount_t *mp, int flags)
          * access to the superblock.
          */
         sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);
-        extra_flags = XBF_LOCK | XBF_FS_MANAGED | XBF_MAPPED;
 
-        bp = xfs_buf_read(mp->m_ddev_targp, XFS_SB_DADDR, BTOBB(sector_size),
-                          extra_flags);
-        if (!bp || XFS_BUF_ISERROR(bp)) {
-                xfs_fs_mount_cmn_err(flags, "SB read failed");
-                error = bp ? XFS_BUF_GETERROR(bp) : ENOMEM;
-                goto fail;
+reread:
+        bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
+                                        XFS_SB_DADDR, sector_size, 0);
+        if (!bp) {
+                xfs_fs_mount_cmn_err(flags, "SB buffer read failed");
+                return EIO;
         }
-        ASSERT(XFS_BUF_ISBUSY(bp));
-        ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
 
         /*
          * Initialize the mount structure from the superblock.
          * But first do some basic consistency checking.
          */
         xfs_sb_from_disk(&mp->m_sb, XFS_BUF_TO_SBP(bp));
-
         error = xfs_mount_validate_sb(mp, &(mp->m_sb), flags);
         if (error) {
                 xfs_fs_mount_cmn_err(flags, "SB validate failed");
-                goto fail;
+                goto release_buf;
         }
 
         /*
@@ -691,7 +686,7 @@ xfs_readsb(xfs_mount_t *mp, int flags)
                         "device supports only %u byte sectors (not %u)",
                         sector_size, mp->m_sb.sb_sectsize);
                 error = ENOSYS;
-                goto fail;
+                goto release_buf;
         }
 
         /*
@@ -699,33 +694,20 @@ xfs_readsb(xfs_mount_t *mp, int flags)
          * re-read the superblock so the buffer is correctly sized.
          */
         if (sector_size < mp->m_sb.sb_sectsize) {
-                XFS_BUF_UNMANAGE(bp);
                 xfs_buf_relse(bp);
                 sector_size = mp->m_sb.sb_sectsize;
-                bp = xfs_buf_read(mp->m_ddev_targp, XFS_SB_DADDR,
-                                  BTOBB(sector_size), extra_flags);
-                if (!bp || XFS_BUF_ISERROR(bp)) {
-                        xfs_fs_mount_cmn_err(flags, "SB re-read failed");
-                        error = bp ? XFS_BUF_GETERROR(bp) : ENOMEM;
-                        goto fail;
-                }
-                ASSERT(XFS_BUF_ISBUSY(bp));
-                ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
+                goto reread;
         }
 
         /* Initialize per-cpu counters */
         xfs_icsb_reinit_counters(mp);
 
         mp->m_sb_bp = bp;
-        xfs_buf_relse(bp);
-        ASSERT(XFS_BUF_VALUSEMA(bp) > 0);
+        xfs_buf_unlock(bp);
         return 0;
 
- fail:
-        if (bp) {
-                XFS_BUF_UNMANAGE(bp);
-                xfs_buf_relse(bp);
-        }
+release_buf:
+        xfs_buf_relse(bp);
         return error;
 }
 
@@ -2005,18 +1987,13 @@ xfs_getsb(
  */
 void
 xfs_freesb(
-        xfs_mount_t     *mp)
+        struct xfs_mount        *mp)
 {
-        xfs_buf_t       *bp;
+        struct xfs_buf          *bp = mp->m_sb_bp;
 
-        /*
-         * Use xfs_getsb() so that the buffer will be locked
-         * when we call xfs_buf_relse().
-         */
-        bp = xfs_getsb(mp, 0);
-        XFS_BUF_UNMANAGE(bp);
-        xfs_buf_relse(bp);
+        xfs_buf_lock(bp);
         mp->m_sb_bp = NULL;
+        xfs_buf_relse(bp);
 }
 
 /*