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| author | Boris Burkov <boris@bur.io> | 2020-11-18 15:06:22 -0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2020-12-09 19:16:08 +0100 |
| commit | 948462294577a3870c407c16d89bb2314f0b0cfb (patch) | |
| tree | 3ef24bbc5ecac9ddc42ea657752d01c6de81947c /fs/btrfs/super.c | |
| parent | 8b228324a8ce03083a034dfa784bc10696ce7489 (diff) | |
| download | lwn-948462294577a3870c407c16d89bb2314f0b0cfb.tar.gz lwn-948462294577a3870c407c16d89bb2314f0b0cfb.zip | |
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 <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/super.c')
| -rw-r--r-- | fs/btrfs/super.c | 10 |
1 files changed, 7 insertions, 3 deletions
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) |