linux/fs/cachefiles/daemon.c, branch v6.7

cachefiles: enable on-demand read mode

2022-05-17T16:11:18Z

Enable on-demand read mode by adding an optional parameter to the "bind" command. On-demand mode will be turned on when this parameter is "ondemand", i.e. "bind ondemand". Otherwise cachefiles will work in the original mode. Signed-off-by: Jeffle Xu Link: https://lore.kernel.org/r/20220509074028.74954-7-jefflexu@linux.alibaba.com Acked-by: David Howells Signed-off-by: Gao Xiang

cachefiles: unbind cachefiles gracefully in on-demand mode

2022-05-17T16:11:17Z

Add a refcount to avoid the deadlock in on-demand read mode. The on-demand read mode will pin the corresponding cachefiles object for each anonymous fd. The cachefiles object is unpinned when the anonymous fd gets closed. When the user daemon exits and the fd of "/dev/cachefiles" device node gets closed, it will wait for all cahcefiles objects getting withdrawn. Then if there's any anonymous fd getting closed after the fd of the device node, the user daemon will hang forever, waiting for all objects getting withdrawn. To fix this, add a refcount indicating if there's any object pinned by anonymous fds. The cachefiles cache gets unbound and withdrawn when the refcount is decreased to 0. It won't change the behaviour of the original mode, in which case the cachefiles cache gets unbound and withdrawn as long as the fd of the device node gets closed. Signed-off-by: Jeffle Xu Link: https://lore.kernel.org/r/20220509074028.74954-4-jefflexu@linux.alibaba.com Acked-by: David Howells Signed-off-by: Gao Xiang

cachefiles: notify the user daemon when looking up cookie

2022-05-17T16:11:17Z

Fscache/CacheFiles used to serve as a local cache for a remote networking fs. A new on-demand read mode will be introduced for CacheFiles, which can boost the scenario where on-demand read semantics are needed, e.g. container image distribution. The essential difference between these two modes is seen when a cache miss occurs: In the original mode, the netfs will fetch the data from the remote server and then write it to the cache file; in on-demand read mode, fetching the data and writing it into the cache is delegated to a user daemon. As the first step, notify the user daemon when looking up cookie. In this case, an anonymous fd is sent to the user daemon, through which the user daemon can write the fetched data to the cache file. Since the user daemon may move the anonymous fd around, e.g. through dup(), an object ID uniquely identifying the cache file is also attached. Also add one advisory flag (FSCACHE_ADV_WANT_CACHE_SIZE) suggesting that the cache file size shall be retrieved at runtime. This helps the scenario where one cache file contains multiple netfs files, e.g. for the purpose of deduplication. In this case, netfs itself has no idea the size of the cache file, whilst the user daemon should give the hint on it. Signed-off-by: Jeffle Xu Link: https://lore.kernel.org/r/20220509074028.74954-3-jefflexu@linux.alibaba.com Acked-by: David Howells Signed-off-by: Gao Xiang

cachefiles: set default tag name if it's unspecified

2022-01-21T21:36:28Z

fscache_acquire_cache() requires a non-empty name, while 'tag ' command is optional for cachefilesd. Thus set default tag name if it's unspecified to avoid the regression of cachefilesd. The logic is the same with that before rewritten. Signed-off-by: Jeffle Xu Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/164251399914.3435901.4761991152407411408.stgit@warthog.procyon.org.uk/ # v1

fscache, cachefiles: Display stats of no-space events

2022-01-07T13:43:13Z

Add stat counters of no-space events that caused caching not to happen and display in /proc/fs/fscache/stats. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819653216.215744.17210522251617386509.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906958369.143852.7257100711818401748.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967166917.1823006.14842444049198947892.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021566184.640689.4417328329632709265.stgit@warthog.procyon.org.uk/ # v4

cachefiles: Allow cachefiles to actually function

2022-01-07T13:43:07Z

Remove the block that allowed cachefiles to be compiled but prevented it from actually starting a cache. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819649497.215744.2872504990762846767.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906956491.143852.4951522864793559189.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967165374.1823006.14248189932202373809.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021564379.640689.7921380491176827442.stgit@warthog.procyon.org.uk/ # v4

cachefiles: Implement backing file wrangling

2022-01-07T13:42:40Z

Implement the wrangling of backing files, including the following pieces: (1) Lookup and creation of a file on disk, using a tmpfile if the file isn't yet present. The file is then opened, sized for DIO and the file handle is attached to the cachefiles_object struct. The inode is marked to indicate that it's in use by a kernel service. (2) Invalidation of an object, creating a tmpfile and switching the file pointer in the cachefiles object. (3) Committing a file to disk, including setting the coherency xattr on it and, if necessary, creating a hard link to it. Note that this would be a good place to use Omar Sandoval's vfs_link() with AT_LINK_REPLACE[1] as I may have to unlink an old file before I can link a tmpfile into place. (4) Withdrawal of open objects when a cache is being withdrawn or a cookie is relinquished. This involves committing or discarding the file. Changes ======= ver #2: - Fix logging of wrong error[1]. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/20211203094950.GA2480@kili/ [1] Link: https://lore.kernel.org/r/163819644097.215744.4505389616742411239.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906949512.143852.14222856795032602080.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967158526.1823006.17482695321424642675.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021557060.640689.16373541458119269871.stgit@warthog.procyon.org.uk/ # v4

cachefiles: Implement culling daemon commands

2022-01-07T13:42:35Z

Implement the ability for the userspace daemon to try and cull a file or directory in the cache. Two daemon commands are implemented: (1) The "inuse" command. This queries if a file is in use or whether it can be deleted. It checks the S_KERNEL_FILE flag on the inode referred to by the specified filename. (2) The "cull" command. This asks for a file or directory to be removed, where removal means either unlinking it or moving it to the graveyard directory for userspace to dismantle. Changes ======= ver #2: - Fix logging of wrong error[1]. - Need to unmark an inode we've moved to the graveyard before unlocking. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/20211203094950.GA2480@kili/ [1] Link: https://lore.kernel.org/r/163819643179.215744.13641580295708315695.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906945705.143852.8177595531814485350.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967155792.1823006.1088936326902550910.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021555037.640689.9472627499842585255.stgit@warthog.procyon.org.uk/ # v4

cachefiles: Implement volume support

2022-01-07T13:41:53Z

Implement support for creating the directory layout for a volume on disk and setting up and withdrawing volume caching. Each volume has a directory named for the volume key under the root of the cache (prefixed with an 'I' to indicate to cachefilesd that it's an index) and then creates a bunch of hash bucket subdirectories under that (named as '@' plus a hex number) in which cookie files will be created. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819635314.215744.13081522301564537723.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906936397.143852.17788457778396467161.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967143860.1823006.7185205806080225038.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021545212.640689.5064821392307582927.stgit@warthog.procyon.org.uk/ # v4

cachefiles: Implement cache registration and withdrawal

2022-01-07T13:41:46Z

Do the following: (1) Fill out cachefiles_daemon_add_cache() so that it sets up the cache directories and registers the cache with cachefiles. (2) Add a function to do the top-level part of cache withdrawal and unregistration. (3) Add a function to sync a cache. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819633175.215744.10857127598041268340.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906935445.143852.15545194974036410029.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967142904.1823006.244055483596047072.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021543872.640689.14370017789605073222.stgit@warthog.procyon.org.uk/ # v4