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 stable@vger.kernel.org.

thanks,

greg k-h

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

From c26b5aa8ef0d46035060fded475e6ab957b9f69f Mon Sep 17 00:00:00 2001

From: Andreas Gruenbacher agruenba@redhat.com 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: stable@vger.kernel.org # v4.19+ Signed-off-by: Andreas Gruenbacher agruenba@redhat.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c index 38d88fcb6988..0d643306c255 100644 --- a/fs/gfs2/bmap.c +++ b/fs/gfs2/bmap.c @@ -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; }