xfs: convert buffer verifiers to an ops structure.

To separate the verifiers from iodone functions and associate read
and write verifiers at the same time, introduce a buffer verifier
operations structure to the xfs_buf.

This avoids the need for assigning the write verifier, clearing the
iodone function and re-running ioend processing in the read
verifier, and gets rid of the nasty "b_pre_io" name for the write
verifier function pointer. If we ever need to, it will also be
easier to add further content specific callbacks to a buffer with an
ops structure in place.

We also avoid needing to export verifier functions, instead we
can simply export the ops structures for those that are needed
outside the function they are defined in.

This patch also fixes a directory block readahead verifier issue
it exposed.

This patch also adds ops callbacks to the inode/alloc btree blocks
initialised by growfs. These will need more work before they will
work with CRCs.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Phil White <pwhite@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 37 insertions, 26 deletions

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index bd1a948ee39c..26673a0b20e7 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -571,7 +571,7 @@ found:
                 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
                 ASSERT(bp->b_iodone == NULL);
                 bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
-                bp->b_pre_io = NULL;
+                bp->b_ops = NULL;
         }
 
         trace_xfs_buf_find(bp, flags, _RET_IP_);
@@ -657,7 +657,7 @@ xfs_buf_read_map(
         struct xfs_buf_map      *map,
         int                     nmaps,
         xfs_buf_flags_t         flags,
-        xfs_buf_iodone_t        verify)
+        const struct xfs_buf_ops *ops)
 {
         struct xfs_buf          *bp;
 
@@ -669,7 +669,7 @@ xfs_buf_read_map(
 
                 if (!XFS_BUF_ISDONE(bp)) {
                         XFS_STATS_INC(xb_get_read);
-                        bp->b_iodone = verify;
+                        bp->b_ops = ops;
                         _xfs_buf_read(bp, flags);
                 } else if (flags & XBF_ASYNC) {
                         /*
@@ -696,13 +696,13 @@ xfs_buf_readahead_map(
         struct xfs_buftarg      *target,
         struct xfs_buf_map      *map,
         int                     nmaps,
-        xfs_buf_iodone_t        verify)
+        const struct xfs_buf_ops *ops)
 {
         if (bdi_read_congested(target->bt_bdi))
                 return;
 
         xfs_buf_read_map(target, map, nmaps,
-                     XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD, verify);
+                     XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD, ops);
 }
 
 /*
@@ -715,7 +715,7 @@ xfs_buf_read_uncached(
         xfs_daddr_t             daddr,
         size_t                  numblks,
         int                     flags,
-        xfs_buf_iodone_t        verify)
+        const struct xfs_buf_ops *ops)
 {
         struct xfs_buf          *bp;
 
@@ -728,7 +728,7 @@ xfs_buf_read_uncached(
         bp->b_bn = daddr;
         bp->b_maps[0].bm_bn = daddr;
         bp->b_flags |= XBF_READ;
-        bp->b_iodone = verify;
+        bp->b_ops = ops;
 
         xfsbdstrat(target->bt_mount, bp);
         xfs_buf_iowait(bp);
@@ -1001,27 +1001,37 @@ STATIC void
 xfs_buf_iodone_work(
         struct work_struct      *work)
 {
-        xfs_buf_t               *bp =
+        struct xfs_buf          *bp =
                 container_of(work, xfs_buf_t, b_iodone_work);
+        bool                    read = !!(bp->b_flags & XBF_READ);
+
+        bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
+        if (read && bp->b_ops)
+                bp->b_ops->verify_read(bp);
 
         if (bp->b_iodone)
                 (*(bp->b_iodone))(bp);
         else if (bp->b_flags & XBF_ASYNC)
                 xfs_buf_relse(bp);
+        else {
+                ASSERT(read && bp->b_ops);
+                complete(&bp->b_iowait);
+        }
 }
 
 void
 xfs_buf_ioend(
-        xfs_buf_t               *bp,
-        int                     schedule)
+        struct xfs_buf  *bp,
+        int             schedule)
 {
+        bool            read = !!(bp->b_flags & XBF_READ);
+
         trace_xfs_buf_iodone(bp, _RET_IP_);
 
-        bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
         if (bp->b_error == 0)
                 bp->b_flags |= XBF_DONE;
 
-        if ((bp->b_iodone) || (bp->b_flags & XBF_ASYNC)) {
+        if (bp->b_iodone || (read && bp->b_ops) || (bp->b_flags & XBF_ASYNC)) {
                 if (schedule) {
                         INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work);
                         queue_work(xfslogd_workqueue, &bp->b_iodone_work);
@@ -1029,6 +1039,7 @@ xfs_buf_ioend(
                         xfs_buf_iodone_work(&bp->b_iodone_work);
                 }
         } else {
+                bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
                 complete(&bp->b_iowait);
         }
 }
@@ -1316,6 +1327,20 @@ _xfs_buf_ioapply(
                         rw |= REQ_FUA;
                 if (bp->b_flags & XBF_FLUSH)
                         rw |= REQ_FLUSH;
+
+                /*
+                 * Run the write verifier callback function if it exists. If
+                 * this function fails it will mark the buffer with an error and
+                 * the IO should not be dispatched.
+                 */
+                if (bp->b_ops) {
+                        bp->b_ops->verify_write(bp);
+                        if (bp->b_error) {
+                                xfs_force_shutdown(bp->b_target->bt_mount,
+                                                   SHUTDOWN_CORRUPT_INCORE);
+                                return;
+                        }
+                }
         } else if (bp->b_flags & XBF_READ_AHEAD) {
                 rw = READA;
         } else {
@@ -1326,20 +1351,6 @@ _xfs_buf_ioapply(
         rw |= REQ_META;
 
         /*
-         * run the pre-io callback function if it exists. If this function
-         * fails it will mark the buffer with an error and the IO should
-         * not be dispatched.
-         */
-        if (bp->b_pre_io) {
-                bp->b_pre_io(bp);
-                if (bp->b_error) {
-                        xfs_force_shutdown(bp->b_target->bt_mount,
-                                           SHUTDOWN_CORRUPT_INCORE);
-                        return;
-                }
-        }
-
-        /*
          * Walk all the vectors issuing IO on them. Set up the initial offset
          * into the buffer and the desired IO size before we start -
          * _xfs_buf_ioapply_vec() will modify them appropriately for each