ocfs2: Wrap virtual block reads in ocfs2_read_virt_blocks()

The ocfs2_read_dir_block() function really maps an inode's virtual
blocks to physical ones before calling ocfs2_read_blocks().  Let's
extract that to common code, because other places might want to do that.

Other than the block number being virtual, ocfs2_read_virt_blocks()
takes the same arguments as ocfs2_read_blocks().  It converts those
virtual block numbers to physical before calling ocfs2_read_blocks()
directly.  If the blocks asked for are discontiguous, this can mean
multiple calls to ocfs2_read_blocks(), but this is mostly hidden from
the caller.

Like ocfs2_read_blocks(), the caller can pass in an existing
buffer_head.  This is usually done to pick up some readahead I/O.
ocfs2_read_virt_blocks() checks the buffer_head's block number
against the extent map - it must match.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
index 0bd9d96..f2bb1a0 100644 (file)
--- a/fs/ocfs2/extent_map.c
+++ b/fs/ocfs2/extent_map.c
@@ -806,3 +806,74 @@ out:
 
        return ret;
 }
+
+int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr,
+                          struct buffer_head *bhs[], int flags,
+                          int (*validate)(struct super_block *sb,
+                                          struct buffer_head *bh))
+{
+       int rc = 0;
+       u64 p_block, p_count;
+       int i, count, done = 0;
+
+       mlog_entry("(inode = %p, v_block = %llu, nr = %d, bhs = %p, "
+                  "flags = %x, validate = %p)\n",
+                  inode, (unsigned long long)v_block, nr, bhs, flags,
+                  validate);
+
+       if (((v_block + nr - 1) << inode->i_sb->s_blocksize_bits) >=
+           i_size_read(inode)) {
+               BUG_ON(!(flags & OCFS2_BH_READAHEAD));
+               goto out;
+       }
+
+       while (done < nr) {
+               down_read(&OCFS2_I(inode)->ip_alloc_sem);
+               rc = ocfs2_extent_map_get_blocks(inode, v_block + done,
+                                                &p_block, &p_count, NULL);
+               up_read(&OCFS2_I(inode)->ip_alloc_sem);
+               if (rc) {
+                       mlog_errno(rc);
+                       break;
+               }
+
+               if (!p_block) {
+                       rc = -EIO;
+                       mlog(ML_ERROR,
+                            "Inode #%llu contains a hole at offset %llu\n",
+                            (unsigned long long)OCFS2_I(inode)->ip_blkno,
+                            (unsigned long long)(v_block + done) <<
+                            inode->i_sb->s_blocksize_bits);
+                       break;
+               }
+
+               count = nr - done;
+               if (p_count < count)
+                       count = p_count;
+
+               /*
+                * If the caller passed us bhs, they should have come
+                * from a previous readahead call to this function.  Thus,
+                * they should have the right b_blocknr.
+                */
+               for (i = 0; i < count; i++) {
+                       if (!bhs[done + i])
+                               continue;
+                       BUG_ON(bhs[done + i]->b_blocknr != (p_block + i));
+               }
+
+               rc = ocfs2_read_blocks(inode, p_block, count, bhs + done,
+                                      flags, validate);
+               if (rc) {
+                       mlog_errno(rc);
+                       break;
+               }
+               done += count;
+       }
+
+out:
+       mlog_exit(rc);
+       return rc;
+}
+
+

diff --git a/fs/ocfs2/extent_map.h b/fs/ocfs2/extent_map.h
index 1c4aa8b..b7dd973 100644 (file)
--- a/fs/ocfs2/extent_map.h
+++ b/fs/ocfs2/extent_map.h
@@ -57,4 +57,28 @@ int ocfs2_xattr_get_clusters(struct inode *inode, u32 v_cluster,
                             u32 *p_cluster, u32 *num_clusters,
                             struct ocfs2_extent_list *el);
 
+int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr,
+                          struct buffer_head *bhs[], int flags,
+                          int (*validate)(struct super_block *sb,
+                                          struct buffer_head *bh));
+static inline int ocfs2_read_virt_block(struct inode *inode, u64 v_block,
+                                       struct buffer_head **bh,
+                                       int (*validate)(struct super_block *sb,
+                                                       struct buffer_head *bh))
+{
+       int status = 0;
+
+       if (bh == NULL) {
+               printk("ocfs2: bh == NULL\n");
+               status = -EINVAL;
+               goto bail;
+       }
+
+       status = ocfs2_read_virt_blocks(inode, v_block, 1, bh, 0, validate);
+
+bail:
+       return status;
+}
+
+
 #endif  /* _EXTENT_MAP_H */