[GFS2] Tidy up meta_io code

Fix a bug in the directory reading code, where we might have dereferenced
a NULL pointer in case of OOM. Updated the directory code to use the new
& improved version of gfs2_meta_ra() which now returns the first block
that was being read. Previously it was releasing it requiring following
code to grab the block again at each point it was called.

Also turned off readahead on directory lookups since we are reading a
hash table, and therefore reading the entries in order is very
unlikely. Readahead is still used for all other calls to the
directory reading function (e.g. when growing the hash table).

Removed the DIO_START constant. Everywhere this was used, it was
used to unconditionally start i/o aside from a couple of places, so
I've removed it and made the couple of exceptions to this rule into
separate functions.

Also hunted through the other DIO flags and removed them as arguments
from functions which were always called with the same combination of
arguments.

Updated gfs2_meta_indirect_buffer to be a bit more efficient and
hopefully also be a bit easier to read.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 26 insertions, 30 deletions

diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c
index 739028688270..40e94ac0b93d 100644
--- a/fs/gfs2/dir.c
+++ b/fs/gfs2/dir.c
@@ -106,7 +106,7 @@ static int gfs2_dir_get_existing_buffer(struct gfs2_inode *ip, u64 block,
 	struct buffer_head *bh;
 	int error;
 
-	error = gfs2_meta_read(ip->i_gl, block, DIO_START | DIO_WAIT, &bh);
+	error = gfs2_meta_read(ip->i_gl, block, DIO_WAIT, &bh);
 	if (error)
 		return error;
 	if (gfs2_metatype_check(GFS2_SB(&ip->i_inode), bh, GFS2_METATYPE_JD)) {
@@ -246,7 +246,7 @@ fail:
 }
 
 static int gfs2_dir_read_stuffed(struct gfs2_inode *ip, char *buf,
-				 unsigned int offset, unsigned int size)
+				 u64 offset, unsigned int size)
 {
 	struct buffer_head *dibh;
 	int error;
@@ -271,8 +271,8 @@ static int gfs2_dir_read_stuffed(struct gfs2_inode *ip, char *buf,
  *
  * Returns: The amount of data actually copied or the error
  */
-static int gfs2_dir_read_data(struct gfs2_inode *ip, char *buf,
-			      u64 offset, unsigned int size)
+static int gfs2_dir_read_data(struct gfs2_inode *ip, char *buf, u64 offset,
+			      unsigned int size, unsigned ra)
 {
 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 	u64 lblock, dblock;
@@ -291,8 +291,7 @@ static int gfs2_dir_read_data(struct gfs2_inode *ip, char *buf,
 		return 0;
 
 	if (gfs2_is_stuffed(ip))
-		return gfs2_dir_read_stuffed(ip, buf, (unsigned int)offset,
-					     size);
+		return gfs2_dir_read_stuffed(ip, buf, offset, size);
 
 	if (gfs2_assert_warn(sdp, gfs2_is_jdata(ip)))
 		return -EINVAL;
@@ -313,34 +312,31 @@ static int gfs2_dir_read_data(struct gfs2_inode *ip, char *buf,
 			new = 0;
 			error = gfs2_extent_map(&ip->i_inode, lblock, &new,
 						&dblock, &extlen);
-			if (error)
+			if (error || !dblock)
 				goto fail;
+			BUG_ON(extlen < 1);
+			if (!ra)
+				extlen = 1;
+			bh = gfs2_meta_ra(ip->i_gl, dblock, extlen);
 		}
-
-		if (extlen > 1)
-			gfs2_meta_ra(ip->i_gl, dblock, extlen);
-
-		if (dblock) {
-			if (new)
-				error = gfs2_dir_get_new_buffer(ip, dblock, &bh);
-			else
-				error = gfs2_dir_get_existing_buffer(ip, dblock, &bh);
+		if (!bh) {
+			error = gfs2_meta_read(ip->i_gl, dblock, DIO_WAIT, &bh);
 			if (error)
 				goto fail;
-			dblock++;
-			extlen--;
-		} else
-			bh = NULL;
-
+		}
+		error = gfs2_metatype_check(sdp, bh, GFS2_METATYPE_JD);
+		if (error) {
+			brelse(bh);
+			goto fail;
+		}
+		dblock++;
+		extlen--;
 		memcpy(buf, bh->b_data + o, amount);
 		brelse(bh);
-		if (error)
-			goto fail;
-
+		bh = NULL;
 		buf += amount;
 		copied += amount;
 		lblock++;
-
 		o = sizeof(struct gfs2_meta_header);
 	}
 
@@ -701,7 +697,7 @@ static int get_leaf(struct gfs2_inode *dip, u64 leaf_no,
 {
 	int error;
 
-	error = gfs2_meta_read(dip->i_gl, leaf_no, DIO_START | DIO_WAIT, bhp);
+	error = gfs2_meta_read(dip->i_gl, leaf_no, DIO_WAIT, bhp);
 	if (!error && gfs2_metatype_check(GFS2_SB(&dip->i_inode), *bhp, GFS2_METATYPE_LF)) {
 		/* printk(KERN_INFO "block num=%llu\n", leaf_no); */
 		error = -EIO;
@@ -727,7 +723,7 @@ static int get_leaf_nr(struct gfs2_inode *dip, u32 index,
 
 	error = gfs2_dir_read_data(dip, (char *)&leaf_no,
 				    index * sizeof(u64),
-				    sizeof(u64));
+				    sizeof(u64), 0);
 	if (error != sizeof(u64))
 		return (error < 0) ? error : -EIO;
 
@@ -1095,7 +1091,7 @@ static int dir_double_exhash(struct gfs2_inode *dip)
 	for (block = dip->i_di.di_size >> sdp->sd_hash_bsize_shift; block--;) {
 		error = gfs2_dir_read_data(dip, (char *)buf,
 					    block * sdp->sd_hash_bsize,
-					    sdp->sd_hash_bsize);
+					    sdp->sd_hash_bsize, 1);
 		if (error != sdp->sd_hash_bsize) {
 			if (error >= 0)
 				error = -EIO;
@@ -1375,7 +1371,7 @@ static int dir_e_read(struct inode *inode, u64 *offset, void *opaque,
 		if (ht_offset_cur != ht_offset) {
 			error = gfs2_dir_read_data(dip, (char *)lp,
 						ht_offset * sizeof(u64),
-						sdp->sd_hash_bsize);
+						sdp->sd_hash_bsize, 1);
 			if (error != sdp->sd_hash_bsize) {
 				if (error >= 0)
 					error = -EIO;
@@ -1745,7 +1741,7 @@ static int foreach_leaf(struct gfs2_inode *dip, leaf_call_t lc, void *data)
 		if (ht_offset_cur != ht_offset) {
 			error = gfs2_dir_read_data(dip, (char *)lp,
 						ht_offset * sizeof(u64),
-						sdp->sd_hash_bsize);
+						sdp->sd_hash_bsize, 1);
 			if (error != sdp->sd_hash_bsize) {
 				if (error >= 0)
 					error = -EIO;