Commit 3c181c12 authored by Anand Jain's avatar Anand Jain Committed by David Sterba
Browse files

btrfs: use proper endianness accessors for super_copy 



The fs_info::super_copy is a byte copy of the on-disk structure and all
members must use the accessor macros/functions to obtain the right
value.  This was missing in update_super_roots and in sysfs readers.

Moving between opposite endianness hosts will report bogus numbers in
sysfs, and mount may fail as the root will not be restored correctly. If
the filesystem is always used on a same endian host, this will not be a
problem.

Fix this by using the btrfs_set_super...() functions to set
fs_info::super_copy values, and for the sysfs, use the cached
fs_info::nodesize/sectorsize values.

CC: stable@vger.kernel.org
Fixes: df93589a ("btrfs: export more from FS_INFO to sysfs")
Signed-off-by: default avatarAnand Jain <anand.jain@oracle.com>
Reviewed-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 92e222df

fs/btrfs/sysfs.c

+3 −5
Original line number Diff line number Diff line
@@ -423,7 +423,7 @@ static ssize_t btrfs_nodesize_show(struct kobject *kobj, 
{

	struct btrfs_fs_info *fs_info = to_fs_info(kobj);



	return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->super_copy->nodesize);

	return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->nodesize);

}



BTRFS_ATTR(, nodesize, btrfs_nodesize_show);
@@ -433,8 +433,7 @@ static ssize_t btrfs_sectorsize_show(struct kobject *kobj, 
{

	struct btrfs_fs_info *fs_info = to_fs_info(kobj);



	return snprintf(buf, PAGE_SIZE, "%u\n",

			fs_info->super_copy->sectorsize);

	return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->sectorsize);

}



BTRFS_ATTR(, sectorsize, btrfs_sectorsize_show);
@@ -444,8 +443,7 @@ static ssize_t btrfs_clone_alignment_show(struct kobject *kobj, 
{

	struct btrfs_fs_info *fs_info = to_fs_info(kobj);



	return snprintf(buf, PAGE_SIZE, "%u\n",

			fs_info->super_copy->sectorsize);

	return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->sectorsize);

}



BTRFS_ATTR(, clone_alignment, btrfs_clone_alignment_show);

fs/btrfs/transaction.c

+12 −8
Original line number Diff line number Diff line
@@ -1722,19 +1722,23 @@ static void update_super_roots(struct btrfs_fs_info *fs_info) 


	super = fs_info->super_copy;



	/* update latest btrfs_super_block::chunk_root refs */

	root_item = &fs_info->chunk_root->root_item;

	super->chunk_root = root_item->bytenr;

	super->chunk_root_generation = root_item->generation;

	super->chunk_root_level = root_item->level;

	btrfs_set_super_chunk_root(super, root_item->bytenr);

	btrfs_set_super_chunk_root_generation(super, root_item->generation);

	btrfs_set_super_chunk_root_level(super, root_item->level);



	/* update latest btrfs_super_block::root refs */

	root_item = &fs_info->tree_root->root_item;

	super->root = root_item->bytenr;

	super->generation = root_item->generation;

	super->root_level = root_item->level;

	btrfs_set_super_root(super, root_item->bytenr);

	btrfs_set_super_generation(super, root_item->generation);

	btrfs_set_super_root_level(super, root_item->level);



	if (btrfs_test_opt(fs_info, SPACE_CACHE))

		super->cache_generation = root_item->generation;

		btrfs_set_super_cache_generation(super, root_item->generation);

	if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))

		super->uuid_tree_generation = root_item->generation;

		btrfs_set_super_uuid_tree_generation(super,

						     root_item->generation);

}



int btrfs_transaction_in_commit(struct btrfs_fs_info *info)

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