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FAILED: patch "[PATCH] gfs2: Fix iomap buffer head reference counting bug" failed to apply to 4.19-stable tree

PATCH [email protected] 1 participant 1 message Nov 19, 2018

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The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From c26b5aa8ef0d46035060fded475e6ab957b9f69f Mon Sep 17 00:00:00 2001

From: Andreas Gruenbacher <[email protected]>
Date: Sun, 11 Nov 2018 11:15:21 +0000
Subject: [PATCH] gfs2: Fix iomap buffer head reference counting bug

GFS2 passes the inode buffer head (dibh) from gfs2_iomap_begin to gfs2_iomap_end in iomap->private. It sets that private pointer in gfs2_iomap_get. Users of gfs2_iomap_get other than gfs2_iomap_begin would have to release iomap->private, but this isn't done correctly, leading to a leak of buffer head references.

To fix this, move the code for setting iomap->private from gfs2_iomap_get to gfs2_iomap_begin.

Fixes 64bc06bb32 ("gfs2: iomap buffered write support")
Cc [email protected] # v4.19+
Signed-off-by Andreas Gruenbacher <[email protected]>
Signed-off-by Linus Torvalds <[email protected]>
fs/gfs2/bmap.c +17 -23
index 38d88fcb6988..0d643306c255 100644
@@ -826,7 +826,7 @@ static int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
 	ret = gfs2_meta_inode_buffer(ip, &dibh);
 	if (ret)
 		goto unlock;
-	iomap->private = dibh;
+	mp->mp_bh[0] = dibh;
 
 	if (gfs2_is_stuffed(ip)) {
 		if (flags & IOMAP_WRITE) {

@@ -863,9 +863,6 @@ static int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
 	len = lblock_stop - lblock + 1;
 	iomap->length = len << inode->i_blkbits;
 
-	get_bh(dibh);
-	mp->mp_bh[0] = dibh;
-
 	height = ip->i_height;
 	while ((lblock + 1) * sdp->sd_sb.sb_bsize > sdp->sd_heightsize[height])
 		height++;

@@ -898,8 +895,6 @@ static int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
 	iomap->bdev = inode->i_sb->s_bdev;
 unlock:
 	up_read(&ip->i_rw_mutex);
-	if (ret && dibh)
-		brelse(dibh);
 	return ret;
 
 do_alloc:

@@ -980,9 +975,9 @@ static void gfs2_iomap_journaled_page_done(struct inode *inode, loff_t pos,
 
 static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
 				  loff_t length, unsigned flags,
-				  struct iomap *iomap)
+				  struct iomap *iomap,
+				  struct metapath *mp)
 {
-	struct metapath mp = { .mp_aheight = 1, };
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_sbd *sdp = GFS2_SB(inode);
 	unsigned int data_blocks = 0, ind_blocks = 0, rblocks;

@@ -996,9 +991,9 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
 	unstuff = gfs2_is_stuffed(ip) &&
 		  pos + length > gfs2_max_stuffed_size(ip);
 
-	ret = gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);
+	ret = gfs2_iomap_get(inode, pos, length, flags, iomap, mp);
 	if (ret)
-		goto out_release;
+		goto out_unlock;
 
 	alloc_required = unstuff || iomap->type == IOMAP_HOLE;
 

@@ -1013,7 +1008,7 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
 
 		ret = gfs2_quota_lock_check(ip, &ap);
 		if (ret)
-			goto out_release;
+			goto out_unlock;
 
 		ret = gfs2_inplace_reserve(ip, &ap);
 		if (ret)

@@ -1038,17 +1033,15 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
 		ret = gfs2_unstuff_dinode(ip, NULL);
 		if (ret)
 			goto out_trans_end;
-		release_metapath(&mp);
-		brelse(iomap->private);
-		iomap->private = NULL;
+		release_metapath(mp);
 		ret = gfs2_iomap_get(inode, iomap->offset, iomap->length,
-				     flags, iomap, &mp);
+				     flags, iomap, mp);
 		if (ret)
 			goto out_trans_end;
 	}
 
 	if (iomap->type == IOMAP_HOLE) {
-		ret = gfs2_iomap_alloc(inode, iomap, flags, &mp);
+		ret = gfs2_iomap_alloc(inode, iomap, flags, mp);
 		if (ret) {
 			gfs2_trans_end(sdp);
 			gfs2_inplace_release(ip);

@@ -1056,7 +1049,6 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
 			goto out_qunlock;
 		}
 	}
-	release_metapath(&mp);
 	if (gfs2_is_jdata(ip))
 		iomap->page_done = gfs2_iomap_journaled_page_done;
 	return 0;

@@ -1069,10 +1061,7 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
 out_qunlock:
 	if (alloc_required)
 		gfs2_quota_unlock(ip);
-out_release:
-	if (iomap->private)
-		brelse(iomap->private);
-	release_metapath(&mp);
+out_unlock:
 	gfs2_write_unlock(inode);
 	return ret;
 }

@@ -1088,10 +1077,10 @@ static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
 
 	trace_gfs2_iomap_start(ip, pos, length, flags);
 	if ((flags & IOMAP_WRITE) && !(flags & IOMAP_DIRECT)) {
-		ret = gfs2_iomap_begin_write(inode, pos, length, flags, iomap);
+		ret = gfs2_iomap_begin_write(inode, pos, length, flags, iomap, &mp);
 	} else {
 		ret = gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);
-		release_metapath(&mp);
+
 		/*
 		 * Silently fall back to buffered I/O for stuffed files or if
 		 * we've hot a hole (see gfs2_file_direct_write).

@@ -1100,6 +1089,11 @@ static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
 		    iomap->type != IOMAP_MAPPED)
 			ret = -ENOTBLK;
 	}
+	if (!ret) {
+		get_bh(mp.mp_bh[0]);
+		iomap->private = mp.mp_bh[0];
+	}
+	release_metapath(&mp);
 	trace_gfs2_iomap_end(ip, iomap, ret);
 	return ret;
 }