From: David Howells <dhowells@redhat.com> To: linux-cachefs@redhat.com Cc: dhowells@redhat.com, Trond Myklebust <trondmy@hammerspace.com>, Anna Schumaker <anna.schumaker@netapp.com>, Steve French <sfrench@samba.org>, Dominique Martinet <asmadeus@codewreck.org>, Jeff Layton <jlayton@kernel.org>, Matthew Wilcox <willy@infradead.org>, Alexander Viro <viro@zeniv.linux.org.uk>, Omar Sandoval <osandov@osandov.com>, Linus Torvalds <torvalds@linux-foundation.org>, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 47/64] cachefiles: Implement culling daemon commands Date: Mon, 29 Nov 2021 14:33:51 +0000 [thread overview] Message-ID: <163819643179.215744.13641580295708315695.stgit@warthog.procyon.org.uk> (raw) In-Reply-To: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk> 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. Signed-off-by: David Howells <dhowells@redhat.com> cc: linux-cachefs@redhat.com --- fs/cachefiles/daemon.c | 4 - fs/cachefiles/internal.h | 11 ++ fs/cachefiles/namei.c | 307 ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 320 insertions(+), 2 deletions(-) diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c index 337597a4e30c..985c3f3e6767 100644 --- a/fs/cachefiles/daemon.c +++ b/fs/cachefiles/daemon.c @@ -574,7 +574,7 @@ static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args) goto notdir; cachefiles_begin_secure(cache, &saved_cred); - ret = -ENOANO; // PLACEHOLDER: Do culling + ret = cachefiles_cull(cache, path.dentry, args); cachefiles_end_secure(cache, saved_cred); path_put(&path); @@ -645,7 +645,7 @@ static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args) goto notdir; cachefiles_begin_secure(cache, &saved_cred); - ret = -ENOANO; // PLACEHOLDER: Check if in use + ret = cachefiles_check_in_use(cache, path.dentry, args); cachefiles_end_secure(cache, saved_cred); path_put(&path); diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index ebb39373716b..f2a4ec2f8668 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -189,11 +189,22 @@ extern struct kmem_cache *cachefiles_object_jar; */ extern void cachefiles_unmark_inode_in_use(struct cachefiles_object *object, struct file *file); +extern int cachefiles_bury_object(struct cachefiles_cache *cache, + struct cachefiles_object *object, + struct dentry *dir, + struct dentry *rep, + enum fscache_why_object_killed why); extern struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache, struct dentry *dir, const char *name); extern void cachefiles_put_directory(struct dentry *dir); +extern int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir, + char *filename); + +extern int cachefiles_check_in_use(struct cachefiles_cache *cache, + struct dentry *dir, char *filename); + /* * security.c */ diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c index 2e209e403713..50d0668e54f8 100644 --- a/fs/cachefiles/namei.c +++ b/fs/cachefiles/namei.c @@ -215,3 +215,310 @@ void cachefiles_put_directory(struct dentry *dir) dput(dir); } } + +/* + * Remove a regular file from the cache. + */ +static int cachefiles_unlink(struct cachefiles_cache *cache, + struct cachefiles_object *object, + struct dentry *dir, struct dentry *dentry, + enum fscache_why_object_killed why) +{ + struct path path = { + .mnt = cache->mnt, + .dentry = dir, + }; + int ret; + + trace_cachefiles_unlink(object, dentry, why); + ret = security_path_unlink(&path, dentry); + if (ret < 0) { + cachefiles_io_error(cache, "Unlink security error"); + return ret; + } + + ret = cachefiles_inject_remove_error(); + if (ret == 0) { + ret = vfs_unlink(&init_user_ns, d_backing_inode(dir), dentry, NULL); + if (ret == -EIO) + cachefiles_io_error(cache, "Unlink failed"); + } + if (ret != 0) + trace_cachefiles_vfs_error(object, d_backing_inode(dir), ret, + cachefiles_trace_unlink_error); + return ret; +} + +/* + * Delete an object representation from the cache + * - File backed objects are unlinked + * - Directory backed objects are stuffed into the graveyard for userspace to + * delete + */ +int cachefiles_bury_object(struct cachefiles_cache *cache, + struct cachefiles_object *object, + struct dentry *dir, + struct dentry *rep, + enum fscache_why_object_killed why) +{ + struct dentry *grave, *trap; + struct path path, path_to_graveyard; + char nbuffer[8 + 8 + 1]; + int ret; + + _enter(",'%pd','%pd'", dir, rep); + + if (rep->d_parent != dir) { + inode_unlock(d_inode(dir)); + _leave(" = -ESTALE"); + return -ESTALE; + } + + /* non-directories can just be unlinked */ + if (!d_is_dir(rep)) { + dget(rep); /* Stop the dentry being negated if it's only pinned + * by a file struct. + */ + ret = cachefiles_unlink(cache, object, dir, rep, why); + dput(rep); + + inode_unlock(d_inode(dir)); + _leave(" = %d", ret); + return ret; + } + + /* directories have to be moved to the graveyard */ + _debug("move stale object to graveyard"); + inode_unlock(d_inode(dir)); + +try_again: + /* first step is to make up a grave dentry in the graveyard */ + sprintf(nbuffer, "%08x%08x", + (uint32_t) ktime_get_real_seconds(), + (uint32_t) atomic_inc_return(&cache->gravecounter)); + + /* do the multiway lock magic */ + trap = lock_rename(cache->graveyard, dir); + + /* do some checks before getting the grave dentry */ + if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) { + /* the entry was probably culled when we dropped the parent dir + * lock */ + unlock_rename(cache->graveyard, dir); + _leave(" = 0 [culled?]"); + return 0; + } + + if (!d_can_lookup(cache->graveyard)) { + unlock_rename(cache->graveyard, dir); + cachefiles_io_error(cache, "Graveyard no longer a directory"); + return -EIO; + } + + if (trap == rep) { + unlock_rename(cache->graveyard, dir); + cachefiles_io_error(cache, "May not make directory loop"); + return -EIO; + } + + if (d_mountpoint(rep)) { + unlock_rename(cache->graveyard, dir); + cachefiles_io_error(cache, "Mountpoint in cache"); + return -EIO; + } + + grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer)); + if (IS_ERR(grave)) { + unlock_rename(cache->graveyard, dir); + trace_cachefiles_vfs_error(object, d_inode(cache->graveyard), + PTR_ERR(grave), + cachefiles_trace_lookup_error); + + if (PTR_ERR(grave) == -ENOMEM) { + _leave(" = -ENOMEM"); + return -ENOMEM; + } + + cachefiles_io_error(cache, "Lookup error %ld", PTR_ERR(grave)); + return -EIO; + } + + if (d_is_positive(grave)) { + unlock_rename(cache->graveyard, dir); + dput(grave); + grave = NULL; + cond_resched(); + goto try_again; + } + + if (d_mountpoint(grave)) { + unlock_rename(cache->graveyard, dir); + dput(grave); + cachefiles_io_error(cache, "Mountpoint in graveyard"); + return -EIO; + } + + /* target should not be an ancestor of source */ + if (trap == grave) { + unlock_rename(cache->graveyard, dir); + dput(grave); + cachefiles_io_error(cache, "May not make directory loop"); + return -EIO; + } + + /* attempt the rename */ + path.mnt = cache->mnt; + path.dentry = dir; + path_to_graveyard.mnt = cache->mnt; + path_to_graveyard.dentry = cache->graveyard; + ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0); + if (ret < 0) { + cachefiles_io_error(cache, "Rename security error %d", ret); + } else { + struct renamedata rd = { + .old_mnt_userns = &init_user_ns, + .old_dir = d_inode(dir), + .old_dentry = rep, + .new_mnt_userns = &init_user_ns, + .new_dir = d_inode(cache->graveyard), + .new_dentry = grave, + }; + trace_cachefiles_rename(object, rep, grave, why); + ret = cachefiles_inject_read_error(); + if (ret == 0) + ret = vfs_rename(&rd); + if (ret != 0) + trace_cachefiles_vfs_error(object, d_inode(dir), + PTR_ERR(grave), + cachefiles_trace_rename_error); + if (ret != 0 && ret != -ENOMEM) + cachefiles_io_error(cache, + "Rename failed with error %d", ret); + } + + unlock_rename(cache->graveyard, dir); + dput(grave); + _leave(" = 0"); + return 0; +} + +/* + * Look up an inode to be checked or culled. Return -EBUSY if the inode is + * marked in use. + */ +static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache, + struct dentry *dir, + char *filename) +{ + struct dentry *victim; + int ret = -ENOENT; + + inode_lock_nested(d_inode(dir), I_MUTEX_PARENT); + + victim = lookup_one_len(filename, dir, strlen(filename)); + if (IS_ERR(victim)) + goto lookup_error; + if (d_is_negative(victim)) + goto lookup_put; + if (d_inode(victim)->i_flags & S_KERNEL_FILE) + goto lookup_busy; + return victim; + +lookup_busy: + ret = -EBUSY; +lookup_put: + inode_unlock(d_inode(dir)); + dput(victim); + return ERR_PTR(ret); + +lookup_error: + inode_unlock(d_inode(dir)); + ret = PTR_ERR(victim); + if (ret == -ENOENT) + return ERR_PTR(-ESTALE); /* Probably got retired by the netfs */ + + if (ret == -EIO) { + cachefiles_io_error(cache, "Lookup failed"); + } else if (ret != -ENOMEM) { + pr_err("Internal error: %d\n", ret); + ret = -EIO; + } + + return ERR_PTR(ret); +} + +/* + * Cull an object if it's not in use + * - called only by cache manager daemon + */ +int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir, + char *filename) +{ + struct dentry *victim; + struct inode *inode; + int ret; + + _enter(",%pd/,%s", dir, filename); + + victim = cachefiles_lookup_for_cull(cache, dir, filename); + if (IS_ERR(victim)) + return PTR_ERR(victim); + + /* check to see if someone is using this object */ + inode = d_inode(victim); + inode_lock(inode); + if (inode->i_flags & S_KERNEL_FILE) { + ret = -EBUSY; + } else { + /* Stop the cache from picking it back up */ + inode->i_flags |= S_KERNEL_FILE; + ret = 0; + } + inode_unlock(inode); + if (ret < 0) + goto error_unlock; + + ret = cachefiles_bury_object(cache, NULL, dir, victim, + FSCACHE_OBJECT_WAS_CULLED); + if (ret < 0) + goto error; + + dput(victim); + _leave(" = 0"); + return 0; + +error_unlock: + inode_unlock(d_inode(dir)); +error: + dput(victim); + if (ret == -ENOENT) + return -ESTALE; /* Probably got retired by the netfs */ + + if (ret != -ENOMEM) { + pr_err("Internal error: %d\n", ret); + ret = -EIO; + } + + _leave(" = %d", ret); + return ret; +} + +/* + * Find out if an object is in use or not + * - called only by cache manager daemon + * - returns -EBUSY or 0 to indicate whether an object is in use or not + */ +int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir, + char *filename) +{ + struct dentry *victim; + int ret = 0; + + victim = cachefiles_lookup_for_cull(cache, dir, filename); + if (IS_ERR(victim)) + return PTR_ERR(victim); + + inode_unlock(d_inode(dir)); + dput(victim); + return ret; +}
next prev parent reply other threads:[~2021-11-29 14:36 UTC|newest] Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-11-29 14:22 [PATCH 00/64] fscache, cachefiles: Rewrite David Howells 2021-11-29 14:22 ` [PATCH 01/64] fscache, cachefiles: Disable configuration David Howells 2021-11-29 14:22 ` [PATCH 02/64] cachefiles: Delete the cachefiles driver pending rewrite David Howells 2021-11-29 14:23 ` [PATCH 03/64] fscache: Remove the contents of the fscache driver, " David Howells 2021-11-29 14:23 ` [PATCH 04/64] netfs: Display the netfs inode number in the netfs_read tracepoint David Howells 2021-11-29 14:23 ` [PATCH 05/64] netfs: Pass a flag to ->prepare_write() to say if there's no alloc'd space David Howells 2021-11-29 14:24 ` [PATCH 06/64] fscache: Introduce new driver David Howells 2021-11-29 14:24 ` [PATCH 07/64] fscache: Implement a hash function David Howells 2021-11-29 14:24 ` [PATCH 08/64] fscache: Implement cache registration David Howells 2021-11-29 14:24 ` [PATCH 09/64] fscache: Implement volume registration David Howells 2021-11-29 14:25 ` [PATCH 10/64] fscache: Implement cookie registration David Howells 2021-11-29 14:25 ` [PATCH 11/64] fscache: Implement cache-level access helpers David Howells 2021-11-29 14:25 ` [PATCH 12/64] fscache: Implement volume-level " David Howells 2021-11-29 14:25 ` [PATCH 13/64] fscache: Implement cookie-level " David Howells 2021-11-29 14:26 ` [PATCH 14/64] fscache: Implement functions add/remove a cache David Howells 2021-11-29 14:26 ` [PATCH 15/64] fscache: Provide and use cache methods to lookup/create/free a volume David Howells 2021-11-29 14:26 ` [PATCH 16/64] fscache: Add a function for a cache backend to note an I/O error David Howells 2021-11-29 14:26 ` [PATCH 17/64] fscache: Implement simple cookie state machine David Howells 2021-11-29 14:26 ` [PATCH 18/64] fscache: Implement cookie user counting and resource pinning David Howells 2021-11-29 14:27 ` [PATCH 19/64] fscache: Implement cookie invalidation David Howells 2021-11-29 14:27 ` [PATCH 20/64] fscache: Provide a means to begin an operation David Howells 2021-11-29 14:28 ` [PATCH 21/64] fscache: Count data storage objects in a cache David Howells 2021-11-29 14:28 ` [PATCH 22/64] fscache: Provide read/write stat counters for the cache David Howells 2021-11-29 14:28 ` [PATCH 23/64] fscache: Provide a function to let the netfs update its coherency data David Howells 2021-11-29 14:28 ` [PATCH 24/64] netfs: Pass more information on how to deal with a hole in the cache David Howells 2021-12-06 11:42 ` JeffleXu 2021-12-09 16:49 ` David Howells 2021-11-29 14:28 ` [PATCH 25/64] fscache: Implement raw I/O interface David Howells 2021-11-29 14:29 ` [PATCH 26/64] fscache: Implement higher-level write " David Howells 2021-11-29 14:29 ` [PATCH 27/64] vfs, fscache: Implement pinning of cache usage for writeback David Howells 2021-11-29 14:29 ` [PATCH 28/64] fscache: Provide a function to note the release of a page David Howells 2021-11-29 14:30 ` [PATCH 29/64] fscache: Provide a function to resize a cookie David Howells 2021-11-29 14:30 ` [PATCH 30/64] cachefiles: Introduce rewritten driver David Howells 2021-11-29 14:30 ` [PATCH 31/64] cachefiles: Define structs David Howells 2021-11-29 14:30 ` [PATCH 32/64] cachefiles: Add some error injection support David Howells 2021-11-29 14:30 ` [PATCH 33/64] cachefiles: Add a couple of tracepoints for logging errors David Howells 2021-11-29 14:31 ` [PATCH 34/64] cachefiles: Add cache error reporting macro David Howells 2021-11-29 14:31 ` [PATCH 35/64] cachefiles: Add security derivation David Howells 2021-11-29 14:31 ` [PATCH 36/64] cachefiles: Register a miscdev and parse commands over it David Howells 2021-11-29 14:31 ` [PATCH 37/64] cachefiles: Provide a function to check how much space there is David Howells 2021-11-29 14:31 ` [PATCH 38/64] vfs, cachefiles: Mark a backing file in use with an inode flag David Howells 2021-11-29 14:31 ` [PATCH 39/64] cachefiles: Implement a function to get/create a directory in the cache David Howells 2021-11-29 14:32 ` [PATCH 40/64] cachefiles: Implement cache registration and withdrawal David Howells 2021-11-29 14:32 ` [PATCH 41/64] cachefiles: Implement volume support David Howells 2021-11-29 14:33 ` [PATCH 42/64] cachefiles: Add tracepoints for calls to the VFS David Howells 2021-11-29 14:33 ` [PATCH 43/64] cachefiles: Implement object lifecycle funcs David Howells 2021-11-29 14:33 ` [PATCH 44/64] cachefiles: Implement key to filename encoding David Howells 2021-12-01 5:46 ` JeffleXu 2021-12-01 8:29 ` David Howells 2021-11-29 14:33 ` [PATCH 45/64] cachefiles: Implement metadata/coherency data storage in xattrs David Howells 2021-11-29 14:33 ` [PATCH 46/64] cachefiles: Mark a backing file in use with an inode flag David Howells 2021-11-29 14:33 ` David Howells [this message] 2021-11-29 14:34 ` [PATCH 48/64] cachefiles: Implement backing file wrangling David Howells 2021-11-29 14:34 ` [PATCH 49/64] cachefiles: Implement begin and end I/O operation David Howells 2021-11-29 14:34 ` [PATCH 50/64] cachefiles: Implement cookie resize for truncate David Howells 2021-11-29 14:34 ` [PATCH 51/64] cachefiles: Implement the I/O routines David Howells 2021-11-30 16:15 ` Nathan Chancellor 2021-11-30 21:05 ` David Howells 2021-11-29 14:34 ` [PATCH 52/64] cachefiles: Allow cachefiles to actually function David Howells 2021-11-29 14:35 ` [PATCH 53/64] fscache, cachefiles: Display stats of no-space events David Howells 2021-11-29 14:35 ` [PATCH 54/64] fscache, cachefiles: Display stat of culling events David Howells 2021-11-29 14:36 ` [PATCH 55/64] afs: Handle len being extending over page end in write_begin/write_end David Howells 2021-11-29 14:36 ` [PATCH 56/64] afs: Fix afs_write_end() to handle len > page size David Howells 2021-11-29 14:36 ` [PATCH 57/64] afs: Convert afs to use the new fscache API David Howells 2021-11-29 14:37 ` [PATCH 58/64] afs: Copy local writes to the cache when writing to the server David Howells 2021-11-29 14:37 ` [PATCH 59/64] afs: Skip truncation on the server of data we haven't written yet David Howells 2021-11-29 14:37 ` [PATCH 60/64] 9p: Use fscache indexing rewrite and reenable caching David Howells 2021-11-29 14:37 ` [PATCH 61/64] 9p: Copy local writes to the cache when writing to the server David Howells 2021-11-29 14:38 ` [PATCH 62/64] nfs: Convert to new fscache volume/cookie API David Howells 2021-11-29 14:38 ` [PATCH 63/64] cifs: Support fscache indexing rewrite (untested) David Howells 2021-11-29 14:38 ` [PATCH 64/64] fscache: Rewrite documentation David Howells 2021-11-29 18:12 ` [PATCH 00/64] fscache, cachefiles: Rewrite Linus Torvalds 2021-11-29 21:40 ` [PATCH 35/64] cachefiles: Add security derivation David Howells
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