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>

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>
Joel Becker · Mark Fasheh
1 parent 970e4936d7
Showing 2 changed files with 95 additions and 0 deletions Side-by-side Diff
fs/ocfs2/extent_map.c
fs/ocfs2/extent_map.h
@@ -806,4 +806,73 @@
  
 	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;
+}
@@ -57,5 +57,29 @@
 			     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 */
...	...	@@ -806,4 +806,73 @@
806	806
807	807	return ret;
808	808	}
	809	+
	810	+int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr,
	811	+ struct buffer_head *bhs[], int flags,
	812	+ int (validate)(struct super_block sb,
	813	+ struct buffer_head *bh))
	814	+{
	815	+ int rc = 0;
	816	+ u64 p_block, p_count;
	817	+ int i, count, done = 0;
	818	+
	819	+ mlog_entry("(inode = %p, v_block = %llu, nr = %d, bhs = %p, "
	820	+ "flags = %x, validate = %p)\n",
	821	+ inode, (unsigned long long)v_block, nr, bhs, flags,
	822	+ validate);
	823	+
	824	+ if (((v_block + nr - 1) << inode->i_sb->s_blocksize_bits) >=
	825	+ i_size_read(inode)) {
	826	+ BUG_ON(!(flags & OCFS2_BH_READAHEAD));
	827	+ goto out;
	828	+ }
	829	+
	830	+ while (done < nr) {
	831	+ down_read(&OCFS2_I(inode)->ip_alloc_sem);
	832	+ rc = ocfs2_extent_map_get_blocks(inode, v_block + done,
	833	+ &p_block, &p_count, NULL);
	834	+ up_read(&OCFS2_I(inode)->ip_alloc_sem);
	835	+ if (rc) {
	836	+ mlog_errno(rc);
	837	+ break;
	838	+ }
	839	+
	840	+ if (!p_block) {
	841	+ rc = -EIO;
	842	+ mlog(ML_ERROR,
	843	+ "Inode #%llu contains a hole at offset %llu\n",
	844	+ (unsigned long long)OCFS2_I(inode)->ip_blkno,
	845	+ (unsigned long long)(v_block + done) <<
	846	+ inode->i_sb->s_blocksize_bits);
	847	+ break;
	848	+ }
	849	+
	850	+ count = nr - done;
	851	+ if (p_count < count)
	852	+ count = p_count;
	853	+
	854	+ /*
	855	+ * If the caller passed us bhs, they should have come
	856	+ * from a previous readahead call to this function. Thus,
	857	+ * they should have the right b_blocknr.
	858	+ */
	859	+ for (i = 0; i < count; i++) {
	860	+ if (!bhs[done + i])
	861	+ continue;
	862	+ BUG_ON(bhs[done + i]->b_blocknr != (p_block + i));
	863	+ }
	864	+
	865	+ rc = ocfs2_read_blocks(inode, p_block, count, bhs + done,
	866	+ flags, validate);
	867	+ if (rc) {
	868	+ mlog_errno(rc);
	869	+ break;
	870	+ }
	871	+ done += count;
	872	+ }
	873	+
	874	+out:
	875	+ mlog_exit(rc);
	876	+ return rc;
	877	+}
...	...	@@ -57,5 +57,29 @@
57	57	u32 p_cluster, u32 num_clusters,
58	58	struct ocfs2_extent_list *el);
59	59
	60	+int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr,
	61	+ struct buffer_head *bhs[], int flags,
	62	+ int (validate)(struct super_block sb,
	63	+ struct buffer_head *bh));
	64	+static inline int ocfs2_read_virt_block(struct inode *inode, u64 v_block,
	65	+ struct buffer_head **bh,
	66	+ int (validate)(struct super_block sb,
	67	+ struct buffer_head *bh))
	68	+{
	69	+ int status = 0;
	70	+
	71	+ if (bh == NULL) {
	72	+ printk("ocfs2: bh == NULL\n");
	73	+ status = -EINVAL;
	74	+ goto bail;
	75	+ }
	76	+
	77	+ status = ocfs2_read_virt_blocks(inode, v_block, 1, bh, 0, validate);
	78	+
	79	+bail:
	80	+ return status;
	81	+}
	82	+
	83	+
60	84	#endif /* _EXTENT_MAP_H */