Commit 9567366f authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm cache metadata: fix READ_LOCK macros and cleanup WRITE_LOCK macros 



The READ_LOCK macro was incorrectly returning -EINVAL if
dm_bm_is_read_only() was true -- it will always be true once the cache
metadata transitions to read-only by dm_cache_metadata_set_read_only().

Wrap READ_LOCK and WRITE_LOCK multi-statement macros in do {} while(0).
Also, all accesses of the 'cmd' argument passed to these related macros
are now encapsulated in parenthesis.

A follow-up patch can be developed to eliminate the use of macros in
favor of pure C code.  Avoiding that now given that this needs to apply
to stable@.

Reported-by: default avatarBen Hutchings <ben@decadent.org.uk>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Fixes: d14fcf3d ("dm cache: make sure every metadata function checks fail_io")
Cc: stable@vger.kernel.org
parent 072623de

drivers/md/dm-cache-metadata.c

+40 −24
Original line number Diff line number Diff line
@@ -867,39 +867,55 @@ static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd, 
	return 0;

}



static bool cmd_write_lock(struct dm_cache_metadata *cmd)

{

	down_write(&cmd->root_lock);

	if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {

		up_write(&cmd->root_lock);

		return false;

	}

	return true;

}



#define WRITE_LOCK(cmd)				\

	down_write(&cmd->root_lock); \

	if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) { \

		up_write(&cmd->root_lock); \

	do {					\

		if (!cmd_write_lock((cmd)))	\

			return -EINVAL;		\

	}

	} while(0)



#define WRITE_LOCK_VOID(cmd)			\

	down_write(&cmd->root_lock); \

	if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) { \

		up_write(&cmd->root_lock); \

	do {					\

		if (!cmd_write_lock((cmd)))	\

			return;			\

	}

	} while(0)



#define WRITE_UNLOCK(cmd) \

	up_write(&cmd->root_lock)

	up_write(&(cmd)->root_lock)



static bool cmd_read_lock(struct dm_cache_metadata *cmd)

{

	down_write(&cmd->root_lock);

	if (cmd->fail_io) {

		up_write(&cmd->root_lock);

		return false;

	}

	return true;

}



#define READ_LOCK(cmd)				\

	down_read(&cmd->root_lock); \

	if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) { \

		up_read(&cmd->root_lock); \

	do {					\

		if (!cmd_read_lock((cmd)))	\

			return -EINVAL;		\

	}

	} while(0)



#define READ_LOCK_VOID(cmd)			\

	down_read(&cmd->root_lock); \

	if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) { \

		up_read(&cmd->root_lock); \

	do {					\

		if (!cmd_read_lock((cmd)))	\

			return;			\

	}

	} while(0)



#define READ_UNLOCK(cmd) \

	up_read(&cmd->root_lock)

	up_read(&(cmd)->root_lock)



int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)

{

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