Commit 70499cdf authored by Bob Peterson's avatar Bob Peterson Committed by Andreas Gruenbacher
Browse files

gfs2: Never call gfs2_block_zero_range with an open transaction 



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: 2257e468 ("gfs2: implement gfs2_block_zero_range using iomap_zero_range")
Cc: stable@vger.kernel.org # v5.5+
Signed-off-by: default avatarBob Peterson <rpeterso@redhat.com>
Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent b0be23b2

fs/gfs2/bmap.c

+39 −30
Original line number Diff line number Diff line
@@ -1351,9 +1351,15 @@ 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);

}
@@ -1414,6 +1420,16 @@ 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
@@ -1427,19 +1443,10 @@ 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);
@@ -2448,25 +2455,7 @@ 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);
@@ -2489,6 +2478,26 @@ 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);

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