From 4ddbd7998493ae20b139c8447eb79e029d9a4f03 Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Fri, 18 May 2012 14:30:13 +0100 Subject: [PATCH 31/34] dm block manager: introduce dm_bm_read_only This method switches the block manager to a read-only mode. To be used when dm-thin degrades due to io errors on the metadata device. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer --- drivers/md/persistent-data/dm-block-manager.c | 17 +++++++++++++++++ drivers/md/persistent-data/dm-block-manager.h | 13 +++++++++++++ 2 files changed, 30 insertions(+) Index: linux-2.6/drivers/md/persistent-data/dm-block-manager.c =================================================================== --- linux-2.6.orig/drivers/md/persistent-data/dm-block-manager.c +++ linux-2.6/drivers/md/persistent-data/dm-block-manager.c @@ -364,6 +364,7 @@ static void dm_block_manager_write_callb *--------------------------------------------------------------*/ struct dm_block_manager { struct dm_bufio_client *bufio; + int read_only; }; struct dm_block_manager *dm_block_manager_create(struct block_device *bdev, @@ -385,6 +386,7 @@ struct dm_block_manager *dm_block_manage return NULL; } + bm->read_only = 0; return bm; } EXPORT_SYMBOL_GPL(dm_block_manager_create); @@ -473,6 +475,9 @@ int dm_bm_write_lock(struct dm_block_man void *p; int r; + if (bm->read_only) + return -EPERM; + p = dm_bufio_read(bm->bufio, b, (struct dm_buffer **) result); if (unlikely(IS_ERR(p))) return PTR_ERR(p); @@ -539,6 +544,9 @@ int dm_bm_write_lock_zero(struct dm_bloc struct buffer_aux *aux; void *p; + if (bm->read_only) + return -EPERM; + p = dm_bufio_new(bm->bufio, b, (struct dm_buffer **) result); if (unlikely(IS_ERR(p))) return PTR_ERR(p); @@ -581,6 +589,9 @@ int dm_bm_flush_and_unlock(struct dm_blo { int r; + if (bm->read_only) + return -EPERM; + r = dm_bufio_write_dirty_buffers(bm->bufio); if (unlikely(r)) { dm_bm_unlock(superblock); @@ -592,6 +603,12 @@ int dm_bm_flush_and_unlock(struct dm_blo return dm_bufio_write_dirty_buffers(bm->bufio); } +void dm_bm_read_only(struct dm_block_manager *bm) +{ + bm->read_only = 1; +} +EXPORT_SYMBOL_GPL(dm_bm_read_only); + u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor) { return crc32c(~(u32) 0, data, len) ^ init_xor; Index: linux-2.6/drivers/md/persistent-data/dm-block-manager.h =================================================================== --- linux-2.6.orig/drivers/md/persistent-data/dm-block-manager.h +++ linux-2.6/drivers/md/persistent-data/dm-block-manager.h @@ -108,6 +108,19 @@ int dm_bm_unlock(struct dm_block *b); int dm_bm_flush_and_unlock(struct dm_block_manager *bm, struct dm_block *superblock); +/* + * Switches the bm to a read only mode. Once read-only mode + * has been entered the following functions will return -EPERM. + * + * dm_bm_write_lock + * dm_bm_write_lock_zero + * dm_bm_flush_and_unlock + * + * Additionally you should not use dm_bm_unlock_move, however no error will + * be returned if you do. + */ +void dm_bm_read_only(struct dm_block_manager *bm); + u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor); /*----------------------------------------------------------------*/