[GFS2] Fix bmap to map extents properly

This fix means that bmap will map extents of the length requested
by the VFS rather than guessing at it, or just mapping one block
at a time. The other callers of gfs2_block_map are audited to ensure
they send the correct max extent lengths (i.e. set bh->b_size correctly).

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index cc57f2e..06e9a8c 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -434,8 +434,7 @@
  */
 
 static int gfs2_block_pointers(struct inode *inode, u64 lblock, int create,
-			       struct buffer_head *bh_map, struct metapath *mp,
-			       unsigned int maxlen)
+			       struct buffer_head *bh_map, struct metapath *mp)
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_sbd *sdp = GFS2_SB(inode);
@@ -448,6 +447,7 @@
 	int new = 0;
 	u64 dblock = 0;
 	int boundary;
+	unsigned int maxlen = bh_map->b_size >> inode->i_blkbits;
 
 	BUG_ON(maxlen == 0);
 
@@ -541,13 +541,13 @@
 }
 
 int gfs2_block_map(struct inode *inode, u64 lblock, int create,
-		   struct buffer_head *bh, unsigned int maxlen)
+		   struct buffer_head *bh)
 {
 	struct metapath mp;
 	int ret;
 
 	bmap_lock(inode, create);
-	ret = gfs2_block_pointers(inode, lblock, create, bh, &mp, maxlen);
+	ret = gfs2_block_pointers(inode, lblock, create, bh, &mp);
 	bmap_unlock(inode, create);
 	return ret;
 }
@@ -555,7 +555,7 @@
 int gfs2_extent_map(struct inode *inode, u64 lblock, int *new, u64 *dblock, unsigned *extlen)
 {
 	struct metapath mp;
-	struct buffer_head bh = { .b_state = 0, .b_blocknr = 0, .b_size = 0 };
+	struct buffer_head bh = { .b_state = 0, .b_blocknr = 0 };
 	int ret;
 	int create = *new;
 
@@ -563,8 +563,9 @@
 	BUG_ON(!dblock);
 	BUG_ON(!new);
 
+	bh.b_size = 1 << (inode->i_blkbits + 5);
 	bmap_lock(inode, create);
-	ret = gfs2_block_pointers(inode, lblock, create, &bh, &mp, 32);
+	ret = gfs2_block_pointers(inode, lblock, create, &bh, &mp);
 	bmap_unlock(inode, create);
 	*extlen = bh.b_size >> inode->i_blkbits;
 	*dblock = bh.b_blocknr;
diff --git a/fs/gfs2/bmap.h b/fs/gfs2/bmap.h
index 0fd379b..ac2fd04 100644
--- a/fs/gfs2/bmap.h
+++ b/fs/gfs2/bmap.h
@@ -15,7 +15,7 @@
 struct page;
 
 int gfs2_unstuff_dinode(struct gfs2_inode *ip, struct page *page);
-int gfs2_block_map(struct inode *inode, u64 lblock, int create, struct buffer_head *bh, unsigned int maxlen);
+int gfs2_block_map(struct inode *inode, u64 lblock, int create, struct buffer_head *bh);
 int gfs2_extent_map(struct inode *inode, u64 lblock, int *new, u64 *dblock, unsigned *extlen);
 
 int gfs2_truncatei(struct gfs2_inode *ip, u64 size);
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 72eec65..0cace3d 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -312,10 +312,12 @@
 
 static u64 log_bmap(struct gfs2_sbd *sdp, unsigned int lbn)
 {
+	struct inode *inode = sdp->sd_jdesc->jd_inode;
 	int error;
-	struct buffer_head bh_map;
+	struct buffer_head bh_map = { .b_state = 0, .b_blocknr = 0 };
 
-	error = gfs2_block_map(sdp->sd_jdesc->jd_inode, lbn, 0, &bh_map, 1);
+	bh_map.b_size = 1 << inode->i_blkbits;
+	error = gfs2_block_map(inode, lbn, 0, &bh_map);
 	if (error || !bh_map.b_blocknr)
 		printk(KERN_INFO "error=%d, dbn=%llu lbn=%u", error, bh_map.b_blocknr, lbn);
 	gfs2_assert_withdraw(sdp, !error && bh_map.b_blocknr);
diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index e0599fe..8d5963c 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -65,7 +65,7 @@
 int gfs2_get_block(struct inode *inode, sector_t lblock,
 	           struct buffer_head *bh_result, int create)
 {
-	return gfs2_block_map(inode, lblock, create, bh_result, 32);
+	return gfs2_block_map(inode, lblock, create, bh_result);
 }
 
 /**
@@ -83,7 +83,7 @@
 {
 	int error;
 
-	error = gfs2_block_map(inode, lblock, 0, bh_result, 1);
+	error = gfs2_block_map(inode, lblock, 0, bh_result);
 	if (error)
 		return error;
 	if (bh_result->b_blocknr == 0)
@@ -94,7 +94,7 @@
 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
 				 struct buffer_head *bh_result, int create)
 {
-	return gfs2_block_map(inode, lblock, 0, bh_result, 32);
+	return gfs2_block_map(inode, lblock, 0, bh_result);
 }
 
 /**
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index c69b94a..a3deae7 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -251,7 +251,7 @@
 	unsigned int block, offset;
 	struct buffer_head *bh;
 	int error;
-	struct buffer_head bh_map;
+	struct buffer_head bh_map = { .b_state = 0, .b_blocknr = 0 };
 
 	mutex_lock(&sdp->sd_quota_mutex);
 
@@ -263,7 +263,8 @@
 	block = qd->qd_slot / sdp->sd_qc_per_block;
 	offset = qd->qd_slot % sdp->sd_qc_per_block;;
 
-	error = gfs2_block_map(&ip->i_inode, block, 0, &bh_map, 1);
+	bh_map.b_size = 1 << ip->i_inode.i_blkbits;
+	error = gfs2_block_map(&ip->i_inode, block, 0, &bh_map);
 	if (error)
 		goto fail;
 	error = gfs2_meta_read(ip->i_gl, bh_map.b_blocknr, DIO_WAIT, &bh);
diff --git a/fs/gfs2/recovery.c b/fs/gfs2/recovery.c
index 0a8a4b8..62cd223 100644
--- a/fs/gfs2/recovery.c
+++ b/fs/gfs2/recovery.c
@@ -372,11 +372,12 @@
 	u32 hash;
 	struct buffer_head *bh;
 	int error;
-	struct buffer_head bh_map;
+	struct buffer_head bh_map = { .b_state = 0, .b_blocknr = 0 };
 
 	lblock = head->lh_blkno;
 	gfs2_replay_incr_blk(sdp, &lblock);
-	error = gfs2_block_map(&ip->i_inode, lblock, 0, &bh_map, 1);
+	bh_map.b_size = 1 << ip->i_inode.i_blkbits;
+	error = gfs2_block_map(&ip->i_inode, lblock, 0, &bh_map);
 	if (error)
 		return error;
 	if (!bh_map.b_blocknr) {