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Subject[PATCH 4.19 103/110] gfs2: Fix iomap buffer head reference counting bug
Date
4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andreas Gruenbacher <agruenba@redhat.com>

commit c26b5aa8ef0d46035060fded475e6ab957b9f69f upstream.

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: stable@vger.kernel.org # v4.19+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


---
fs/gfs2/bmap.c | 40 +++++++++++++++++-----------------------
1 file changed, 17 insertions(+), 23 deletions(-)

--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -826,7 +826,7 @@ static int gfs2_iomap_get(struct inode *
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 @@ unstuff:
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 @@ out:
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_do

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
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

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
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
goto out_qunlock;
}
}
- release_metapath(&mp);
if (!gfs2_is_stuffed(ip) && gfs2_is_jdata(ip))
iomap->page_done = gfs2_iomap_journaled_page_done;
return 0;
@@ -1069,10 +1061,7 @@ out_trans_fail:
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

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
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;
}

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