23e12e285a
Add a pair of functions to pin/unpin a cache that we're wanting to do a
high-level access to (such as creating or removing a volume):
bool fscache_begin_cache_access(struct fscache_cache *cache,
enum fscache_access_trace why);
void fscache_end_cache_access(struct fscache_cache *cache,
enum fscache_access_trace why);
The way the access gate works/will work is:
(1) If the cache tests as not live (state is not FSCACHE_CACHE_IS_ACTIVE),
then we return false to indicate access was not permitted.
(2) If the cache tests as live, then we increment the n_accesses count and
then recheck the liveness, ending the access if it ceased to be live.
(3) When we end the access, we decrement n_accesses and wake up the any
waiters if it reaches 0.
(4) Whilst the cache is caching, n_accesses is kept artificially
incremented to prevent wakeups from happening.
(5) When the cache is taken offline, the state is changed to prevent new
accesses, n_accesses is decremented and we wait for n_accesses to
become 0.
Note that some of this is implemented in a later patch.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819593239.215744.7537428720603638088.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906893368.143852.14164004598465617981.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967093977.1823006.6967886507023056409.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021499995.640689.18286203753480287850.stgit@warthog.procyon.org.uk/ # v4
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| acpi | ||
| asm-generic | ||
| clocksource | ||
| crypto | ||
| drm | ||
| dt-bindings | ||
| keys | ||
| kunit | ||
| kvm | ||
| linux | ||
| math-emu | ||
| media | ||
| memory | ||
| misc | ||
| net | ||
| pcmcia | ||
| ras | ||
| rdma | ||
| scsi | ||
| soc | ||
| sound | ||
| target | ||
| trace | ||
| uapi | ||
| vdso | ||
| video | ||
| xen | ||