Commit 46f870d6 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: simulate various I/O and checksum errors when reading metadata 

This allows us to test various error handling code paths

Link: https://lore.kernel.org/r/20191209012317.59398-1-tytso@mit.edu


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 878520ac

fs/ext4/balloc.c

+3 −1
Original line number Diff line number Diff line
@@ -371,7 +371,8 @@ static int ext4_validate_block_bitmap(struct super_block *sb, 
	if (buffer_verified(bh))

		goto verified;

	if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,

			desc, bh))) {

						    desc, bh) ||

		     ext4_simulate_fail(sb, EXT4_SIM_BBITMAP_CRC))) {

		ext4_unlock_group(sb, block_group);

		ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);

		ext4_mark_group_bitmap_corrupted(sb, block_group,
@@ -505,6 +506,7 @@ int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group, 
	if (!desc)

		return -EFSCORRUPTED;

	wait_on_buffer(bh);

	ext4_simulate_fail_bh(sb, bh, EXT4_SIM_BBITMAP_EIO);

	if (!buffer_uptodate(bh)) {

		ext4_set_errno(sb, EIO);

		ext4_error(sb, "Cannot read block bitmap - "

fs/ext4/ext4.h

+37 −0
Original line number Diff line number Diff line
@@ -1557,6 +1557,9 @@ struct ext4_sb_info { 
	/* Barrier between changing inodes' journal flags and writepages ops. */

	struct percpu_rw_semaphore s_journal_flag_rwsem;

	struct dax_device *s_daxdev;

#ifdef CONFIG_EXT4_DEBUG

	unsigned long s_simulate_fail;

#endif

};



static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
@@ -1575,6 +1578,40 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino) 
		 ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count));

}



/*

 * Simulate_fail codes

 */

#define EXT4_SIM_BBITMAP_EIO	1

#define EXT4_SIM_BBITMAP_CRC	2

#define EXT4_SIM_IBITMAP_EIO	3

#define EXT4_SIM_IBITMAP_CRC	4

#define EXT4_SIM_INODE_EIO	5

#define EXT4_SIM_INODE_CRC	6

#define EXT4_SIM_DIRBLOCK_EIO	7

#define EXT4_SIM_DIRBLOCK_CRC	8



static inline bool ext4_simulate_fail(struct super_block *sb,

				     unsigned long code)

{

#ifdef CONFIG_EXT4_DEBUG

	struct ext4_sb_info *sbi = EXT4_SB(sb);



	if (unlikely(sbi->s_simulate_fail == code)) {

		sbi->s_simulate_fail = 0;

		return true;

	}

#endif

	return false;

}



static inline void ext4_simulate_fail_bh(struct super_block *sb,

					 struct buffer_head *bh,

					 unsigned long code)

{

	if (!IS_ERR(bh) && ext4_simulate_fail(sb, code))

		clear_buffer_uptodate(bh);

}



/*

 * Error number codes for s_{first,last}_error_errno

 *

fs/ext4/ialloc.c

+3 −1
Original line number Diff line number Diff line
@@ -94,7 +94,8 @@ static int ext4_validate_inode_bitmap(struct super_block *sb, 
		goto verified;

	blk = ext4_inode_bitmap(sb, desc);

	if (!ext4_inode_bitmap_csum_verify(sb, block_group, desc, bh,

					   EXT4_INODES_PER_GROUP(sb) / 8)) {

					   EXT4_INODES_PER_GROUP(sb) / 8) ||

	    ext4_simulate_fail(sb, EXT4_SIM_IBITMAP_CRC)) {

		ext4_unlock_group(sb, block_group);

		ext4_error(sb, "Corrupt inode bitmap - block_group = %u, "

			   "inode_bitmap = %llu", block_group, blk);
@@ -192,6 +193,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group) 
	get_bh(bh);

	submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, bh);

	wait_on_buffer(bh);

	ext4_simulate_fail_bh(sb, bh, EXT4_SIM_IBITMAP_EIO);

	if (!buffer_uptodate(bh)) {

		put_bh(bh);

		ext4_set_errno(sb, EIO);

fs/ext4/inode.c

+5 −1
Original line number Diff line number Diff line
@@ -4243,6 +4243,8 @@ static int __ext4_get_inode_loc(struct inode *inode, 
	bh = sb_getblk(sb, block);

	if (unlikely(!bh))

		return -ENOMEM;

	if (ext4_simulate_fail(sb, EXT4_SIM_INODE_EIO))

		goto simulate_eio;

	if (!buffer_uptodate(bh)) {

		lock_buffer(bh);
@@ -4341,6 +4343,7 @@ static int __ext4_get_inode_loc(struct inode *inode, 
		blk_finish_plug(&plug);

		wait_on_buffer(bh);

		if (!buffer_uptodate(bh)) {

		simulate_eio:

			ext4_set_errno(inode->i_sb, EIO);

			EXT4_ERROR_INODE_BLOCK(inode, block,

					       "unable to read itable block");
@@ -4555,7 +4558,8 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino, 
					      sizeof(gen));

	}



	if (!ext4_inode_csum_verify(inode, raw_inode, ei)) {

	if (!ext4_inode_csum_verify(inode, raw_inode, ei) ||

	    ext4_simulate_fail(sb, EXT4_SIM_INODE_CRC)) {

		ext4_set_errno(inode->i_sb, EFSBADCRC);

		ext4_error_inode(inode, function, line, 0,

				 "iget: checksum invalid");

fs/ext4/namei.c

+8 −3
Original line number Diff line number Diff line
@@ -109,6 +109,9 @@ static struct buffer_head *__ext4_read_dirblock(struct inode *inode, 
	struct ext4_dir_entry *dirent;

	int is_dx_block = 0;



	if (ext4_simulate_fail(inode->i_sb, EXT4_SIM_DIRBLOCK_EIO))

		bh = ERR_PTR(-EIO);

	else

		bh = ext4_bread(NULL, inode, block, 0);

	if (IS_ERR(bh)) {

		__ext4_warning(inode->i_sb, func, line,
@@ -153,7 +156,8 @@ static struct buffer_head *__ext4_read_dirblock(struct inode *inode, 
	 * caller is sure it should be an index block.

	 */

	if (is_dx_block && type == INDEX) {

		if (ext4_dx_csum_verify(inode, dirent))

		if (ext4_dx_csum_verify(inode, dirent) &&

		    !ext4_simulate_fail(inode->i_sb, EXT4_SIM_DIRBLOCK_CRC))

			set_buffer_verified(bh);

		else {

			ext4_set_errno(inode->i_sb, EFSBADCRC);
@@ -164,7 +168,8 @@ static struct buffer_head *__ext4_read_dirblock(struct inode *inode, 
		}

	}

	if (!is_dx_block) {

		if (ext4_dirblock_csum_verify(inode, bh))

		if (ext4_dirblock_csum_verify(inode, bh) &&

		    !ext4_simulate_fail(inode->i_sb, EXT4_SIM_DIRBLOCK_CRC))

			set_buffer_verified(bh);

		else {

			ext4_set_errno(inode->i_sb, EFSBADCRC);