[PATCH 5.4 012/107] gfs2: Never call gfs2_block_zero_range with an open transaction

Greg Kroah-Hartman
2020-08-24T08:46:36Z

From: Bob Peterson <rpeterso@redhat.com>

[ Upstream commit 70499cdfeb3625c87eebe4f7a7ea06fa7447e5df ]

Before this patch, some functions started transactions then they called
gfs2_block_zero_range. However, gfs2_block_zero_range, like writes, can
start transactions, which results in a recursive transaction error.
For example:

do_shrink
trunc_start
gfs2_trans_begin <------------------------------------------------
gfs2_block_zero_range
iomap_zero_range(inode, from, length, NULL, &gfs2_iomap_ops);
iomap_apply ... iomap_zero_range_actor
iomap_begin
gfs2_iomap_begin
gfs2_iomap_begin_write
actor (iomap_zero_range_actor)
iomap_zero
iomap_write_begin
gfs2_iomap_page_prepare
gfs2_trans_begin <------------------------

This patch reorders the callers of gfs2_block_zero_range so that they
only start their transactions after the call. It also adds a BUG_ON to
ensure this doesn't happen again.

Fixes: 2257e468a63b ("gfs2: implement gfs2_block_zero_range using iomap_zero_range")
Cc: stable@vger.kernel.org # v5.5+
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/gfs2/bmap.c | 69 ++++++++++++++++++++++++++++----------------------
1 file changed, 39 insertions(+), 30 deletions(-)

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 4846e0c47e6af..50fa3e08c02f3 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -1350,9 +1350,15 @@ int gfs2_extent_map(struct inode *inode, u64 lblock, int *new, u64 *dblock, unsi
return ret;
}

+/*
+ * NOTE: Never call gfs2_block_zero_range with an open transaction because it
+ * uses iomap write to perform its actions, which begin their own transactions
+ * (iomap_begin, page_prepare, etc.)
+ */
static int gfs2_block_zero_range(struct inode *inode, loff_t from,
unsigned int length)
{
+ BUG_ON(current->journal_info);
return iomap_zero_range(inode, from, length, NULL, &gfs2_iomap_ops);
}

@@ -1413,6 +1419,16 @@ static int trunc_start(struct inode *inode, u64 newsize)
u64 oldsize = inode->i_size;
int error;

+ if (!gfs2_is_stuffed(ip)) {
+ unsigned int blocksize = i_blocksize(inode);
+ unsigned int offs = newsize & (blocksize - 1);
+ if (offs) {
+ error = gfs2_block_zero_range(inode, newsize,
+ blocksize - offs);
+ if (error)
+ return error;
+ }
+ }
if (journaled)
error = gfs2_trans_begin(sdp, RES_DINODE + RES_JDATA, GFS2_JTRUNC_REVOKES);
else
@@ -1426,19 +1442,10 @@ static int trunc_start(struct inode *inode, u64 newsize)

gfs2_trans_add_meta(ip->i_gl, dibh);

- if (gfs2_is_stuffed(ip)) {
+ if (gfs2_is_stuffed(ip))
gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode) + newsize);
- } else {
- unsigned int blocksize = i_blocksize(inode);
- unsigned int offs = newsize & (blocksize - 1);
- if (offs) {
- error = gfs2_block_zero_range(inode, newsize,
- blocksize - offs);
- if (error)
- goto out;
- }
+ else
ip->i_diskflags |= GFS2_DIF_TRUNC_IN_PROG;
- }

i_size_write(inode, newsize);
ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
@@ -2446,25 +2453,7 @@ int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length)
loff_t start, end;
int error;

- start = round_down(offset, blocksize);
- end = round_up(offset + length, blocksize) - 1;
- error = filemap_write_and_wait_range(inode->i_mapping, start, end);
- if (error)
- return error;
-
- if (gfs2_is_jdata(ip))
- error = gfs2_trans_begin(sdp, RES_DINODE + 2 * RES_JDATA,
- GFS2_JTRUNC_REVOKES);
- else
- error = gfs2_trans_begin(sdp, RES_DINODE, 0);
- if (error)
- return error;
-
- if (gfs2_is_stuffed(ip)) {
- error = stuffed_zero_range(inode, offset, length);
- if (error)
- goto out;
- } else {
+ if (!gfs2_is_stuffed(ip)) {
unsigned int start_off, end_len;

start_off = offset & (blocksize - 1);
@@ -2487,6 +2476,26 @@ int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length)
}
}

+ start = round_down(offset, blocksize);
+ end = round_up(offset + length, blocksize) - 1;
+ error = filemap_write_and_wait_range(inode->i_mapping, start, end);
+ if (error)
+ return error;
+
+ if (gfs2_is_jdata(ip))
+ error = gfs2_trans_begin(sdp, RES_DINODE + 2 * RES_JDATA,
+ GFS2_JTRUNC_REVOKES);
+ else
+ error = gfs2_trans_begin(sdp, RES_DINODE, 0);
+ if (error)
+ return error;
+
+ if (gfs2_is_stuffed(ip)) {
+ error = stuffed_zero_range(inode, offset, length);
+ if (error)
+ goto out;
+ }
+
if (gfs2_is_jdata(ip)) {
BUG_ON(!current->journal_info);
gfs2_journaled_truncate_range(inode, offset, length);
--
2.25.1