From 948462294577a3870c407c16d89bb2314f0b0cfb Mon Sep 17 00:00:00 2001 From: Boris Burkov Date: Wed, 18 Nov 2020 15:06:22 -0800 Subject: [PATCH] btrfs: keep sb cache_generation consistent with space_cache When mounting, btrfs uses the cache_generation in the super block to determine if space cache v1 is in use. However, by mounting with nospace_cache or space_cache=v2, it is possible to disable space cache v1, which does not result in un-setting cache_generation back to 0. In order to base some logic, like mount option printing in /proc/mounts, on the current state of the space cache rather than just the values of the mount option, keep the value of cache_generation consistent with the status of space cache v1. We ensure that cache_generation > 0 iff the file system is using space_cache v1. This requires committing a transaction on any mount which changes whether we are using v1. (v1->nospace_cache, v1->v2, nospace_cache->v1, v2->v1). Since the mechanism for writing out the cache generation is transaction commit, but we want some finer grained control over when we un-set it, we can't just rely on the SPACE_CACHE mount option, and introduce an fs_info flag that mount can use when it wants to unset the generation. Reviewed-by: Josef Bacik Signed-off-by: Boris Burkov Signed-off-by: David Sterba --- fs/btrfs/ctree.h | 3 +++ fs/btrfs/disk-io.c | 8 ++++++++ fs/btrfs/free-space-cache.c | 28 ++++++++++++++++++++++++++++ fs/btrfs/free-space-cache.h | 2 ++ fs/btrfs/super.c | 10 +++++++--- fs/btrfs/transaction.c | 2 ++ 6 files changed, 50 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 331554fd6fd1..2744e13e8eb9 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -559,6 +559,9 @@ enum { /* Indicate that the discard workqueue can service discards. */ BTRFS_FS_DISCARD_RUNNING, + + /* Indicate that we need to cleanup space cache v1 */ + BTRFS_FS_CLEANUP_SPACE_CACHE_V1, }; /* diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 77c7013f69d7..2dcc5e52140c 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2888,6 +2888,7 @@ void btrfs_clear_oneshot_options(struct btrfs_fs_info *fs_info) int btrfs_start_pre_rw_mount(struct btrfs_fs_info *fs_info) { int ret; + const bool cache_opt = btrfs_test_opt(fs_info, SPACE_CACHE); bool clear_free_space_tree = false; if (btrfs_test_opt(fs_info, CLEAR_CACHE) && @@ -2940,6 +2941,12 @@ int btrfs_start_pre_rw_mount(struct btrfs_fs_info *fs_info) } } + if (cache_opt != btrfs_free_space_cache_v1_active(fs_info)) { + ret = btrfs_set_free_space_cache_v1_active(fs_info, cache_opt); + if (ret) + goto out; + } + ret = btrfs_resume_balance_async(fs_info); if (ret) goto out; @@ -3410,6 +3417,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device return ret; } } + set_bit(BTRFS_FS_OPEN, &fs_info->flags); clear_oneshot: diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index fe4b2176a6e8..e71def319655 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -3763,6 +3763,34 @@ int btrfs_trim_block_group_bitmaps(struct btrfs_block_group *block_group, return ret; } +bool btrfs_free_space_cache_v1_active(struct btrfs_fs_info *fs_info) +{ + return btrfs_super_cache_generation(fs_info->super_copy); +} + +int btrfs_set_free_space_cache_v1_active(struct btrfs_fs_info *fs_info, bool active) +{ + struct btrfs_trans_handle *trans; + int ret; + + /* + * update_super_roots will appropriately set + * super_copy->cache_generation based on the SPACE_CACHE option, so all + * we have to do is trigger a transaction commit. + */ + trans = btrfs_start_transaction(fs_info->tree_root, 0); + if (IS_ERR(trans)) + return PTR_ERR(trans); + + if (!active) + set_bit(BTRFS_FS_CLEANUP_SPACE_CACHE_V1, &fs_info->flags); + + ret = btrfs_commit_transaction(trans); + clear_bit(BTRFS_FS_CLEANUP_SPACE_CACHE_V1, &fs_info->flags); + + return ret; +} + #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS /* * Use this if you need to make a bitmap or extent entry specifically, it diff --git a/fs/btrfs/free-space-cache.h b/fs/btrfs/free-space-cache.h index 91d495e31a08..3eff615c30b8 100644 --- a/fs/btrfs/free-space-cache.h +++ b/fs/btrfs/free-space-cache.h @@ -135,6 +135,8 @@ int btrfs_trim_block_group_bitmaps(struct btrfs_block_group *block_group, u64 *trimmed, u64 start, u64 end, u64 minlen, u64 maxlen, bool async); +bool btrfs_free_space_cache_v1_active(struct btrfs_fs_info *fs_info); +int btrfs_set_free_space_cache_v1_active(struct btrfs_fs_info *fs_info, bool active); /* Support functions for running our sanity tests */ #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS int test_add_free_space_entry(struct btrfs_block_group *cache, diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 93514555453b..b2252184305c 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -552,7 +552,6 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options, { substring_t args[MAX_OPT_ARGS]; char *p, *num; - u64 cache_gen; int intarg; int ret = 0; char *compress_type; @@ -562,10 +561,9 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options, bool saved_compress_force; int no_compress = 0; - cache_gen = btrfs_super_cache_generation(info->super_copy); if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE)) btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE); - else if (cache_gen) { + else if (btrfs_free_space_cache_v1_active(info)) { if (btrfs_is_zoned(info)) { btrfs_info(info, "zoned: clearing existing space cache"); @@ -1864,6 +1862,8 @@ static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info, static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info, unsigned long old_opts) { + const bool cache_opt = btrfs_test_opt(fs_info, SPACE_CACHE); + /* * We need to cleanup all defragable inodes if the autodefragment is * close or the filesystem is read only. @@ -1880,6 +1880,10 @@ static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info, else if (btrfs_raw_test_opt(old_opts, DISCARD_ASYNC) && !btrfs_test_opt(fs_info, DISCARD_ASYNC)) btrfs_discard_cleanup(fs_info); + + /* If we toggled space cache */ + if (cache_opt != btrfs_free_space_cache_v1_active(fs_info)) + btrfs_set_free_space_cache_v1_active(fs_info, cache_opt); } static int btrfs_remount(struct super_block *sb, int *flags, char *data) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 6b7156712486..8e0f7a1029c6 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1796,6 +1796,8 @@ static void update_super_roots(struct btrfs_fs_info *fs_info) super->root_level = root_item->level; if (btrfs_test_opt(fs_info, SPACE_CACHE)) super->cache_generation = root_item->generation; + else if (test_bit(BTRFS_FS_CLEANUP_SPACE_CACHE_V1, &fs_info->flags)) + super->cache_generation = 0; if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags)) super->uuid_tree_generation = root_item->generation; } -- 2.20.1