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authorKent Overstreet <kent.overstreet@linux.dev>2022-11-02 17:12:00 -0400
committerKent Overstreet <kent.overstreet@linux.dev>2023-10-22 17:09:51 -0400
commita8b3a677e786fa869d220a6a78b5532a36dc2f4d (patch)
tree3fdbdbb71945ae42dab8dc94971e1c78286eaa63 /fs/bcachefs/inode.c
parent4dcd1cae72912ab08d313ee5a730608022b211d4 (diff)
bcachefs: Nocow support
This adds support for nocow mode, where we do writes in-place when possible. Patch components: - New boolean filesystem and inode option, nocow: note that when nocow is enabled, data checksumming and compression are implicitly disabled - To prevent in-place writes from racing with data moves (data_update.c) or bucket reuse (i.e. a bucket being reused and re-allocated while a nocow write is in flight, we have a new locking mechanism. Buckets can be locked for either data update or data move, using a fixed size hash table of two_state_shared locks. We don't have any chaining, meaning updates and moves to different buckets that hash to the same lock will wait unnecessarily - we'll want to watch for this becoming an issue. - The allocator path also needs to check for in-place writes in flight to a given bucket before giving it out: thus we add another counter to bucket_alloc_state so we can track this. - Fsync now may need to issue cache flushes to block devices instead of flushing the journal. We add a device bitmask to bch_inode_info, ei_devs_need_flush, which tracks devices that need to have flushes issued - note that this will lead to unnecessary flushes when other codepaths have already issued flushes, we may want to replace this with a sequence number. - New nocow write path: look up extents, and if they're writable write to them - otherwise fall back to the normal COW write path. XXX: switch to sequence numbers instead of bitmask for devs needing journal flush XXX: ei_quota_lock being a mutex means bch2_nocow_write_done() needs to run in process context - see if we can improve this Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'fs/bcachefs/inode.c')
-rw-r--r--fs/bcachefs/inode.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/bcachefs/inode.c b/fs/bcachefs/inode.c
index f338cf6fd8b7..a98e40065122 100644
--- a/fs/bcachefs/inode.c
+++ b/fs/bcachefs/inode.c
@@ -892,4 +892,7 @@ void bch2_inode_opts_get(struct bch_io_opts *opts, struct bch_fs *c,
#define x(_name, _bits) opts->_name = inode_opt_get(c, inode, _name);
BCH_INODE_OPTS()
#undef x
+
+ if (opts->nocow)
+ opts->compression = opts->background_compression = opts->data_checksum = opts->erasure_code = 0;
}