Commit 49edd5bf authored by Andreas Gruenbacher's avatar Andreas Gruenbacher Committed by Bob Peterson
Browse files

gfs2: Fixes to "Implement iomap for block_map" 



It turns out that commit 3974320c "Implement iomap for block_map"
introduced a few bugs that trigger occasional failures with xfstest
generic/476:

In gfs2_iomap_begin, we jump to do_alloc when we determine that we are
beyond the end of the allocated metadata (height > ip->i_height).
There, we can end up calling hole_size with a metapath that doesn't
match the current metadata tree, which doesn't make sense.  After
untangling the code at do_alloc, fix this by checking if the block we
are looking for is within the range of allocated metadata.

In addition, add a BUG() in case gfs2_iomap_begin is accidentally called
for reading stuffed files: this is handled separately.  Make sure we
don't truncate iomap->length for reads beyond the end of the file; in
that case, the entire range counts as a hole.

Finally, revert to taking a bitmap write lock when doing allocations.
It's unclear why that change didn't lead to any failures during testing.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: default avatarBob Peterson <rpeterso@redhat.com>
parent 35277995

fs/gfs2/bmap.c

+23 −20
Original line number Diff line number Diff line
@@ -716,7 +716,7 @@ int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length, 
	__be64 *ptr;

	sector_t lblock;

	sector_t lend;

	int ret;

	int ret = 0;

	int eob;

	unsigned int len;

	struct buffer_head *bh;
@@ -728,13 +728,15 @@ int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length, 
		goto out;

	}



	if ((flags & IOMAP_REPORT) && gfs2_is_stuffed(ip)) {

	if (gfs2_is_stuffed(ip)) {

		if (flags & IOMAP_REPORT) {

			gfs2_stuffed_iomap(inode, iomap);

			if (pos >= iomap->length)

			return -ENOENT;

		ret = 0;

				ret = -ENOENT;

			goto out;

		}

		BUG_ON(!(flags & IOMAP_WRITE));

	}



	lblock = pos >> inode->i_blkbits;

	lend = (pos + length + sdp->sd_sb.sb_bsize - 1) >> inode->i_blkbits;
@@ -744,7 +746,7 @@ int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length, 
	iomap->type = IOMAP_HOLE;

	iomap->length = (u64)(lend - lblock) << inode->i_blkbits;

	iomap->flags = IOMAP_F_MERGED;

	bmap_lock(ip, 0);

	bmap_lock(ip, flags & IOMAP_WRITE);



	/*

	 * Directory data blocks have a struct gfs2_meta_header header, so the
@@ -787,27 +789,28 @@ int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length, 
		iomap->flags |= IOMAP_F_BOUNDARY;

	iomap->length = (u64)len << inode->i_blkbits;



	ret = 0;



out_release:

	release_metapath(&mp);

	bmap_unlock(ip, 0);

	bmap_unlock(ip, flags & IOMAP_WRITE);

out:

	trace_gfs2_iomap_end(ip, iomap, ret);

	return ret;



do_alloc:

	if (!(flags & IOMAP_WRITE)) {

		if (pos >= i_size_read(inode)) {

	if (flags & IOMAP_WRITE) {

		ret = gfs2_iomap_alloc(inode, iomap, flags, &mp);

	} else if (flags & IOMAP_REPORT) {

		loff_t size = i_size_read(inode);

		if (pos >= size)

			ret = -ENOENT;

			goto out_release;

		}

		ret = 0;

		else if (height <= ip->i_height)

			iomap->length = hole_size(inode, lblock, &mp);

		else

			iomap->length = size - pos;

	} else {

		if (height <= ip->i_height)

			iomap->length = hole_size(inode, lblock, &mp);

		goto out_release;

	}



	ret = gfs2_iomap_alloc(inode, iomap, flags, &mp);

	goto out_release;

}

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