[XFS] stop using xfs_itobp in xfs_iread

The only caller of xfs_itobp that doesn't have i_blkno setup is now
the initial inode read.  It needs access to the whole xfs_imap so using
xfs_inotobp is not an option.  Instead opencode the buffer lookup in
xfs_iread and kill all the functionality for the initial map from
xfs_itobp.

(First sent on October 21st)

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>

1 files changed, 34 insertions, 46 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 083395cd675b..1d5c28b144ae 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -262,15 +262,11 @@ xfs_inotobp(
  * If a non-zero error is returned, then the contents of bpp and
  * dipp are undefined.
  *
- * If the inode is new and has not yet been initialized, use xfs_imap()
- * to determine the size and location of the buffer to read from disk.
- * If the inode has already been mapped to its buffer and read in once,
- * then use the mapping information stored in the inode rather than
- * calling xfs_imap().  This allows us to avoid the overhead of looking
- * at the inode btree for small block file systems (see xfs_dilocate()).
- * We can tell whether the inode has been mapped in before by comparing
- * its disk block address to 0.  Only uninitialized inodes will have
- * 0 for the disk block address.
+ * The inode is expected to already been mapped to its buffer and read
+ * in once, thus we can use the mapping information stored in the inode
+ * rather than calling xfs_imap().  This allows us to avoid the overhead
+ * of looking at the inode btree for small block file systems
+ * (see xfs_dilocate()).
  */
 int
 xfs_itobp(
@@ -279,40 +275,19 @@ xfs_itobp(
         xfs_inode_t     *ip,
         xfs_dinode_t    **dipp,
         xfs_buf_t       **bpp,
-        xfs_daddr_t     bno,
-        uint            imap_flags,
         uint            buf_flags)
 {
         xfs_imap_t      imap;
         xfs_buf_t       *bp;
         int             error;
 
-        if (ip->i_blkno == (xfs_daddr_t)0) {
-                imap.im_blkno = bno;
-                error = xfs_imap(mp, tp, ip->i_ino, &imap,
-                                        XFS_IMAP_LOOKUP | imap_flags);
-                if (error)
-                        return error;
+        ASSERT(ip->i_blkno != 0);
 
-                /*
-                 * Fill in the fields in the inode that will be used to
-                 * map the inode to its buffer from now on.
-                 */
-                ip->i_blkno = imap.im_blkno;
-                ip->i_len = imap.im_len;
-                ip->i_boffset = imap.im_boffset;
-        } else {
-                /*
-                 * We've already mapped the inode once, so just use the
-                 * mapping that we saved the first time.
-                 */
-                imap.im_blkno = ip->i_blkno;
-                imap.im_len = ip->i_len;
-                imap.im_boffset = ip->i_boffset;
-        }
-        ASSERT(bno == 0 || bno == imap.im_blkno);
+        imap.im_blkno = ip->i_blkno;
+        imap.im_len = ip->i_len;
+        imap.im_boffset = ip->i_boffset;
 
-        error = xfs_imap_to_bp(mp, tp, &imap, &bp, buf_flags, imap_flags);
+        error = xfs_imap_to_bp(mp, tp, &imap, &bp, buf_flags, 0);
         if (error)
                 return error;
 
@@ -882,6 +857,7 @@ xfs_iread(
         xfs_buf_t       *bp;
         xfs_dinode_t    *dip;
         xfs_inode_t     *ip;
+        xfs_imap_t      imap;
         int             error;
 
         ip = xfs_inode_alloc(mp, ino);
@@ -889,15 +865,27 @@ xfs_iread(
                 return ENOMEM;
 
         /*
-         * Get pointer's to the on-disk inode and the buffer containing it.
-         * If the inode number refers to a block outside the file system
-         * then xfs_itobp() will return NULL.  In this case we should
-         * return NULL as well.  Set i_blkno to 0 so that xfs_itobp() will
-         * know that this is a new incore inode.
+         * Get pointers to the on-disk inode and the buffer containing it.
          */
-        error = xfs_itobp(mp, tp, ip, &dip, &bp, bno, imap_flags, XFS_BUF_LOCK);
+        imap.im_blkno = bno;
+        error = xfs_imap(mp, tp, ip->i_ino, &imap,
+                                XFS_IMAP_LOOKUP | imap_flags);
+        if (error)
+                goto out_destroy_inode;
+
+        /*
+         * Fill in the fields in the inode that will be used to
+         * map the inode to its buffer from now on.
+         */
+        ip->i_blkno = imap.im_blkno;
+        ip->i_len = imap.im_len;
+        ip->i_boffset = imap.im_boffset;
+        ASSERT(bno == 0 || bno == imap.im_blkno);
+
+        error = xfs_imap_to_bp(mp, tp, &imap, &bp, XFS_BUF_LOCK, imap_flags);
         if (error)
                 goto out_destroy_inode;
+        dip = (xfs_dinode_t *)xfs_buf_offset(bp, imap.im_boffset);
 
         /*
          * If we got something that isn't an inode it means someone
@@ -1878,7 +1866,7 @@ xfs_iunlink(
                  * Here we put the head pointer into our next pointer,
                  * and then we fall through to point the head at us.
                  */
-                error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
+                error = xfs_itobp(mp, tp, ip, &dip, &ibp, XFS_BUF_LOCK);
                 if (error)
                         return error;
 
@@ -1960,7 +1948,7 @@ xfs_iunlink_remove(
                  * of dealing with the buffer when there is no need to
                  * change it.
                  */
-                error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
+                error = xfs_itobp(mp, tp, ip, &dip, &ibp, XFS_BUF_LOCK);
                 if (error) {
                         cmn_err(CE_WARN,
                                 "xfs_iunlink_remove: xfs_itobp()  returned an error %d on %s.  Returning error.",
@@ -2022,7 +2010,7 @@ xfs_iunlink_remove(
                  * Now last_ibp points to the buffer previous to us on
                  * the unlinked list.  Pull us from the list.
                  */
-                error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
+                error = xfs_itobp(mp, tp, ip, &dip, &ibp, XFS_BUF_LOCK);
                 if (error) {
                         cmn_err(CE_WARN,
                                 "xfs_iunlink_remove: xfs_itobp()  returned an error %d on %s.  Returning error.",
@@ -2277,7 +2265,7 @@ xfs_ifree(
 
         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
-        error = xfs_itobp(ip->i_mount, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
+        error = xfs_itobp(ip->i_mount, tp, ip, &dip, &ibp, XFS_BUF_LOCK);
         if (error)
                 return error;
 
@@ -3191,7 +3179,7 @@ xfs_iflush(
         /*
          * Get the buffer containing the on-disk inode.
          */
-        error = xfs_itobp(mp, NULL, ip, &dip, &bp, 0, 0,
+        error = xfs_itobp(mp, NULL, ip, &dip, &bp,
                                 noblock ? XFS_BUF_TRYLOCK : XFS_BUF_LOCK);
         if (error || !bp) {
                 xfs_ifunlock(ip);