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[PATCH 3/6] merge xfs_imap into xfs_dilocate

To: xfs@xxxxxxxxxxx
Subject: [PATCH 3/6] merge xfs_imap into xfs_dilocate
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Mon, 27 Oct 2008 09:41:24 -0400
User-agent: quilt/0.46-1
xfs_imap is the only caller of xfs_dilocate and doesn't add any significant
value.  Merge the two functions and document the various cases we have for
inode cluster lookup in the new xfs_imap.

Also remove the unused im_agblkno and im_ioffset fields from struct xfs_imap
while we're at it.


Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Index: linux-2.6-xfs/fs/xfs/xfs_ialloc.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_ialloc.c      2008-10-25 13:28:32.000000000 
+0200
+++ linux-2.6-xfs/fs/xfs/xfs_ialloc.c   2008-10-25 13:28:50.000000000 +0200
@@ -40,6 +40,7 @@
 #include "xfs_rtalloc.h"
 #include "xfs_error.h"
 #include "xfs_bmap.h"
+#include "xfs_imap.h"
 
 
 /*
@@ -1196,36 +1197,28 @@ error0:
 }
 
 /*
- * Return the location of the inode in bno/off, for mapping it into a buffer.
+ * Return the location of the inode in imap, for mapping it into a buffer.
  */
-/*ARGSUSED*/
 int
-xfs_dilocate(
-       xfs_mount_t     *mp,    /* file system mount structure */
-       xfs_trans_t     *tp,    /* transaction pointer */
+xfs_imap(
+       xfs_mount_t      *mp,   /* file system mount structure */
+       xfs_trans_t      *tp,   /* transaction pointer */
        xfs_ino_t       ino,    /* inode to locate */
-       xfs_fsblock_t   *bno,   /* output: block containing inode */
-       int             *len,   /* output: num blocks in inode cluster */
-       int             *off,   /* output: index in block of inode */
-       uint            flags)  /* flags concerning inode lookup */
+       struct xfs_imap *imap,  /* location map structure */
+       uint            flags)  /* flags for inode btree lookup */
 {
        xfs_agblock_t   agbno;  /* block number of inode in the alloc group */
-       xfs_buf_t       *agbp;  /* agi buffer */
        xfs_agino_t     agino;  /* inode number within alloc group */
        xfs_agnumber_t  agno;   /* allocation group number */
        int             blks_per_cluster; /* num blocks per inode cluster */
        xfs_agblock_t   chunk_agbno;    /* first block in inode chunk */
-       xfs_agino_t     chunk_agino;    /* first agino in inode chunk */
-       __int32_t       chunk_cnt;      /* count of free inodes in chunk */
-       xfs_inofree_t   chunk_free;     /* mask of free inodes in chunk */
        xfs_agblock_t   cluster_agbno;  /* first block in inode cluster */
-       xfs_btree_cur_t *cur;   /* inode btree cursor */
        int             error;  /* error code */
-       int             i;      /* temp state */
        int             offset; /* index of inode in its buffer */
        int             offset_agbno;   /* blks from chunk start to inode */
 
        ASSERT(ino != NULLFSINO);
+
        /*
         * Split up the inode number into its parts.
         */
@@ -1240,20 +1233,20 @@ xfs_dilocate(
                        return XFS_ERROR(EINVAL);
                if (agno >= mp->m_sb.sb_agcount) {
                        xfs_fs_cmn_err(CE_ALERT, mp,
-                                       "xfs_dilocate: agno (%d) >= "
+                                       "xfs_imap: agno (%d) >= "
                                        "mp->m_sb.sb_agcount (%d)",
                                        agno,  mp->m_sb.sb_agcount);
                }
                if (agbno >= mp->m_sb.sb_agblocks) {
                        xfs_fs_cmn_err(CE_ALERT, mp,
-                                       "xfs_dilocate: agbno (0x%llx) >= "
+                                       "xfs_imap: agbno (0x%llx) >= "
                                        "mp->m_sb.sb_agblocks (0x%lx)",
                                        (unsigned long long) agbno,
                                        (unsigned long) mp->m_sb.sb_agblocks);
                }
                if (ino != XFS_AGINO_TO_INO(mp, agno, agino)) {
                        xfs_fs_cmn_err(CE_ALERT, mp,
-                                       "xfs_dilocate: ino (0x%llx) != "
+                                       "xfs_imap: ino (0x%llx) != "
                                        "XFS_AGINO_TO_INO(mp, agno, agino) "
                                        "(0x%llx)",
                                        ino, XFS_AGINO_TO_INO(mp, agno, agino));
@@ -1262,34 +1255,65 @@ xfs_dilocate(
 #endif /* DEBUG */
                return XFS_ERROR(EINVAL);
        }
-       if ((mp->m_sb.sb_blocksize >= XFS_INODE_CLUSTER_SIZE(mp))) {
+
+       /*
+        * If the inode cluster size is the same as the blocksize or
+        * bigger we get to the buffer by simple arithmetics.
+        */
+       if (XFS_INODE_CLUSTER_SIZE(mp) <= mp->m_sb.sb_blocksize) {
                offset = XFS_INO_TO_OFFSET(mp, ino);
                ASSERT(offset < mp->m_sb.sb_inopblock);
-               *bno = XFS_AGB_TO_FSB(mp, agno, agbno);
-               *off = offset;
-               *len = 1;
+
+               imap->im_blkno = XFS_AGB_TO_DADDR(mp, agno, agbno);
+               imap->im_len = XFS_FSB_TO_BB(mp, 1);
+               imap->im_boffset = (ushort)(offset << mp->m_sb.sb_inodelog);
                return 0;
        }
+
        blks_per_cluster = XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_blocklog;
-       if (*bno != NULLFSBLOCK) {
+
+       /*
+        * If we get a block number passed from bulkstat we can use it to
+        * find the buffer easily.
+        */
+       if (imap->im_blkno) {
                offset = XFS_INO_TO_OFFSET(mp, ino);
                ASSERT(offset < mp->m_sb.sb_inopblock);
-               cluster_agbno = XFS_FSB_TO_AGBNO(mp, *bno);
-               *off = ((agbno - cluster_agbno) * mp->m_sb.sb_inopblock) +
-                       offset;
-               *len = blks_per_cluster;
+
+               cluster_agbno = XFS_DADDR_TO_AGBNO(mp, imap->im_blkno);
+               offset += (agbno - cluster_agbno) * mp->m_sb.sb_inopblock;
+
+               imap->im_len = XFS_FSB_TO_BB(mp, blks_per_cluster);
+               imap->im_boffset = (ushort)(offset << mp->m_sb.sb_inodelog);
                return 0;
        }
+
+       /*
+        * With aligned inodes it's again quite simple and we can skip the
+        * btree lookup.
+        */
        if (mp->m_inoalign_mask) {
                offset_agbno = agbno & mp->m_inoalign_mask;
                chunk_agbno = agbno - offset_agbno;
+
+       /*
+        * Worst case: we actually have to actually perform a lookup in the
+        * inode btree.
+        */
        } else {
+               xfs_btree_cur_t *cur;   /* inode btree cursor */
+               xfs_agino_t     chunk_agino; /* first agino in inode chunk */
+               __int32_t       chunk_cnt; /* count of free inodes in chunk */
+               xfs_inofree_t   chunk_free; /* mask of free inodes in chunk */
+               xfs_buf_t       *agbp;  /* agi buffer */
+               int             i;      /* temp state */
+
                down_read(&mp->m_peraglock);
                error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
                up_read(&mp->m_peraglock);
                if (error) {
 #ifdef DEBUG
-                       xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
+                       xfs_fs_cmn_err(CE_ALERT, mp, "xfs_imap: "
                                        "xfs_ialloc_read_agi() returned "
                                        "error %d, agno %d",
                                        error, agno);
@@ -1299,7 +1323,7 @@ xfs_dilocate(
                cur = xfs_inobt_init_cursor(mp, tp, agbp, agno);
                if ((error = xfs_inobt_lookup_le(cur, agino, 0, 0, &i))) {
 #ifdef DEBUG
-                       xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
+                       xfs_fs_cmn_err(CE_ALERT, mp, "xfs_imap: "
                                        "xfs_inobt_lookup_le() failed");
 #endif /* DEBUG */
                        goto error0;
@@ -1307,18 +1331,19 @@ xfs_dilocate(
                if ((error = xfs_inobt_get_rec(cur, &chunk_agino, &chunk_cnt,
                                &chunk_free, &i))) {
 #ifdef DEBUG
-                       xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
+                       xfs_fs_cmn_err(CE_ALERT, mp, "xfs_imap: "
                                        "xfs_inobt_get_rec() failed");
 #endif /* DEBUG */
                        goto error0;
                }
                if (i == 0) {
 #ifdef DEBUG
-                       xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
+                       xfs_fs_cmn_err(CE_ALERT, mp, "xfs_imap: "
                                        "xfs_inobt_get_rec() failed");
 #endif /* DEBUG */
                        error = XFS_ERROR(EINVAL);
                }
+ error0:
                xfs_trans_brelse(tp, agbp);
                xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
                if (error)
@@ -1326,19 +1351,35 @@ xfs_dilocate(
                chunk_agbno = XFS_AGINO_TO_AGBNO(mp, chunk_agino);
                offset_agbno = agbno - chunk_agbno;
        }
+
        ASSERT(agbno >= chunk_agbno);
        cluster_agbno = chunk_agbno +
                ((offset_agbno / blks_per_cluster) * blks_per_cluster);
        offset = ((agbno - cluster_agbno) * mp->m_sb.sb_inopblock) +
                XFS_INO_TO_OFFSET(mp, ino);
-       *bno = XFS_AGB_TO_FSB(mp, agno, cluster_agbno);
-       *off = offset;
-       *len = blks_per_cluster;
+
+       imap->im_blkno = XFS_AGB_TO_DADDR(mp, agno, cluster_agbno);
+       imap->im_len = XFS_FSB_TO_BB(mp, blks_per_cluster);
+       imap->im_boffset = (ushort)(offset << mp->m_sb.sb_inodelog);
+
+       /*
+        * If the inode number maps to a block outside the bounds
+        * of the file system then return NULL rather than calling
+        * read_buf and panicing when we get an error from the
+        * driver.
+        */
+       if ((imap->im_blkno + imap->im_len) >
+           XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks)) {
+               xfs_fs_cmn_err(CE_ALERT, mp, "xfs_imap: "
+                       "(imap->im_blkno (0x%llx) + imap->im_len (0x%llx)) > "
+                       " XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks) (0x%llx)",
+                       (unsigned long long) imap->im_blkno,
+                       (unsigned long long) imap->im_len,
+                       XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks));
+               return EINVAL;
+       }
+
        return 0;
-error0:
-       xfs_trans_brelse(tp, agbp);
-       xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
-       return error;
 }
 
 /*
Index: linux-2.6-xfs/fs/xfs/xfs_ialloc.h
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_ialloc.h      2008-10-01 06:30:30.000000000 
+0200
+++ linux-2.6-xfs/fs/xfs/xfs_ialloc.h   2008-10-25 13:28:50.000000000 +0200
@@ -20,6 +20,7 @@
 
 struct xfs_buf;
 struct xfs_dinode;
+struct xfs_imap;
 struct xfs_mount;
 struct xfs_trans;
 
@@ -104,17 +105,14 @@ xfs_difree(
        xfs_ino_t       *first_ino);    /* first inode in deleted cluster */
 
 /*
- * Return the location of the inode in bno/len/off,
- * for mapping it into a buffer.
+ * Return the location of the inode in imap, for mapping it into a buffer.
  */
 int
-xfs_dilocate(
+xfs_imap(
        struct xfs_mount *mp,           /* file system mount structure */
        struct xfs_trans *tp,           /* transaction pointer */
        xfs_ino_t       ino,            /* inode to locate */
-       xfs_fsblock_t   *bno,           /* output: block containing inode */
-       int             *len,           /* output: num blocks in cluster*/
-       int             *off,           /* output: index in block of inode */
+       struct xfs_imap *imap,          /* location map structure */
        uint            flags);         /* flags for inode btree lookup */
 
 /*
Index: linux-2.6-xfs/fs/xfs/xfs_imap.h
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_imap.h        2008-10-01 06:30:30.000000000 
+0200
+++ linux-2.6-xfs/fs/xfs/xfs_imap.h     2008-10-25 13:28:50.000000000 +0200
@@ -25,14 +25,7 @@
 typedef struct xfs_imap {
        xfs_daddr_t     im_blkno;       /* starting BB of inode chunk */
        uint            im_len;         /* length in BBs of inode chunk */
-       xfs_agblock_t   im_agblkno;     /* logical block of inode chunk in ag */
-       ushort          im_ioffset;     /* inode offset in block in "inodes" */
        ushort          im_boffset;     /* inode offset in block in bytes */
 } xfs_imap_t;
 
-struct xfs_mount;
-struct xfs_trans;
-int    xfs_imap(struct xfs_mount *, struct xfs_trans *, xfs_ino_t,
-                xfs_imap_t *, uint);
-
 #endif /* __XFS_IMAP_H__ */
Index: linux-2.6-xfs/fs/xfs/xfs_inode.c
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_inode.c       2008-10-25 13:28:32.000000000 
+0200
+++ linux-2.6-xfs/fs/xfs/xfs_inode.c    2008-10-25 13:28:50.000000000 +0200
@@ -266,7 +266,7 @@ xfs_inotobp(
  * 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()).
+ * (see xfs_imap()).
  */
 int
 xfs_itobp(
@@ -2505,64 +2505,6 @@ xfs_idata_realloc(
        ASSERT(ifp->if_bytes <= XFS_IFORK_SIZE(ip, whichfork));
 }
 
-
-
-
-/*
- * Map inode to disk block and offset.
- *
- * mp -- the mount point structure for the current file system
- * tp -- the current transaction
- * ino -- the inode number of the inode to be located
- * imap -- this structure is filled in with the information necessary
- *      to retrieve the given inode from disk
- * flags -- flags to pass to xfs_dilocate indicating whether or not
- *      lookups in the inode btree were OK or not
- */
-int
-xfs_imap(
-       xfs_mount_t     *mp,
-       xfs_trans_t     *tp,
-       xfs_ino_t       ino,
-       xfs_imap_t      *imap,
-       uint            flags)
-{
-       xfs_fsblock_t   fsbno;
-       int             len;
-       int             off;
-       int             error;
-
-       fsbno = imap->im_blkno ?
-               XFS_DADDR_TO_FSB(mp, imap->im_blkno) : NULLFSBLOCK;
-       error = xfs_dilocate(mp, tp, ino, &fsbno, &len, &off, flags);
-       if (error)
-               return error;
-
-       imap->im_blkno = XFS_FSB_TO_DADDR(mp, fsbno);
-       imap->im_len = XFS_FSB_TO_BB(mp, len);
-       imap->im_agblkno = XFS_FSB_TO_AGBNO(mp, fsbno);
-       imap->im_ioffset = (ushort)off;
-       imap->im_boffset = (ushort)(off << mp->m_sb.sb_inodelog);
-
-       /*
-        * If the inode number maps to a block outside the bounds
-        * of the file system then return NULL rather than calling
-        * read_buf and panicing when we get an error from the
-        * driver.
-        */
-       if ((imap->im_blkno + imap->im_len) >
-           XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks)) {
-               xfs_fs_cmn_err(CE_ALERT, mp, "xfs_imap: "
-                       "(imap->im_blkno (0x%llx) + imap->im_len (0x%llx)) > "
-                       " XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks) (0x%llx)",
-                       (unsigned long long) imap->im_blkno,
-                       (unsigned long long) imap->im_len,
-                       XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks));
-               return EINVAL;
-       }
-       return 0;
-}
-
 void
 xfs_idestroy_fork(
        xfs_inode_t     *ip,
Index: linux-2.6-xfs/fs/xfs/xfs_inode.h
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_inode.h       2008-10-25 13:28:32.000000000 
+0200
+++ linux-2.6-xfs/fs/xfs/xfs_inode.h    2008-10-25 13:28:50.000000000 +0200
@@ -157,7 +157,7 @@ typedef struct xfs_icdinode {
 #define        XFS_IFEXTIREC   0x08    /* Indirection array of extent blocks */
 
 /*
- * Flags for xfs_inotobp, xfs_imap() and xfs_dilocate().
+ * Flags for xfs_inotobp and xfs_imap().
  */
 #define XFS_IMAP_BULKSTAT      0x1
 

-- 

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