kernel/linux.git/fs/cachefiles/namei.c, branch v6.1.174

cachefiles: fix dentry leak in cachefiles_open_file()

2024-10-17T13:22:01+00:00

commit da6ef2dffe6056aad3435e6cf7c6471c2a62187c upstream. A dentry leak may be caused when a lookup cookie and a cull are concurrent: P1 | P2 ----------------------------------------------------------- cachefiles_lookup_cookie cachefiles_look_up_object lookup_one_positive_unlocked // get dentry cachefiles_cull inode->i_flags |= S_KERNEL_FILE; cachefiles_open_file cachefiles_mark_inode_in_use __cachefiles_mark_inode_in_use can_use = false if (!(inode->i_flags & S_KERNEL_FILE)) can_use = true return false return false // Returns an error but doesn't put dentry After that the following WARNING will be triggered when the backend folder is umounted: ================================================================== BUG: Dentry 000000008ad87947{i=7a,n=Dx_1_1.img} still in use (1) [unmount of ext4 sda] WARNING: CPU: 4 PID: 359261 at fs/dcache.c:1767 umount_check+0x5d/0x70 CPU: 4 PID: 359261 Comm: umount Not tainted 6.6.0-dirty #25 RIP: 0010:umount_check+0x5d/0x70 Call Trace: d_walk+0xda/0x2b0 do_one_tree+0x20/0x40 shrink_dcache_for_umount+0x2c/0x90 generic_shutdown_super+0x20/0x160 kill_block_super+0x1a/0x40 ext4_kill_sb+0x22/0x40 deactivate_locked_super+0x35/0x80 cleanup_mnt+0x104/0x160 ================================================================== Whether cachefiles_open_file() returns true or false, the reference count obtained by lookup_positive_unlocked() in cachefiles_look_up_object() should be released. Therefore release that reference count in cachefiles_look_up_object() to fix the above issue and simplify the code. Fixes: 1f08c925e7a3 ("cachefiles: Implement backing file wrangling") Cc: stable@kernel.org Signed-off-by: Baokun Li Link: https://lore.kernel.org/r/20240829083409.3788142-1-libaokun@huaweicloud.com Acked-by: David Howells Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

mm, netfs, fscache: stop read optimisation when folio removed from pagecache

2024-01-10T16:10:31+00:00

[ Upstream commit b4fa966f03b7401ceacd4ffd7227197afb2b8376 ] Fscache has an optimisation by which reads from the cache are skipped until we know that (a) there's data there to be read and (b) that data isn't entirely covered by pages resident in the netfs pagecache. This is done with two flags manipulated by fscache_note_page_release(): if (... test_bit(FSCACHE_COOKIE_HAVE_DATA, &cookie->flags) && test_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags)) clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags); where the NO_DATA_TO_READ flag causes cachefiles_prepare_read() to indicate that netfslib should download from the server or clear the page instead. The fscache_note_page_release() function is intended to be called from ->releasepage() - but that only gets called if PG_private or PG_private_2 is set - and currently the former is at the discretion of the network filesystem and the latter is only set whilst a page is being written to the cache, so sometimes we miss clearing the optimisation. Fix this by following Willy's suggestion[1] and adding an address_space flag, AS_RELEASE_ALWAYS, that causes filemap_release_folio() to always call ->release_folio() if it's set, even if PG_private or PG_private_2 aren't set. Note that this would require folio_test_private() and page_has_private() to become more complicated. To avoid that, in the places[*] where these are used to conditionalise calls to filemap_release_folio() and try_to_release_page(), the tests are removed the those functions just jumped to unconditionally and the test is performed there. [*] There are some exceptions in vmscan.c where the check guards more than just a call to the releaser. I've added a function, folio_needs_release() to wrap all the checks for that. AS_RELEASE_ALWAYS should be set if a non-NULL cookie is obtained from fscache and cleared in ->evict_inode() before truncate_inode_pages_final() is called. Additionally, the FSCACHE_COOKIE_NO_DATA_TO_READ flag needs to be cleared and the optimisation cancelled if a cachefiles object already contains data when we open it. [dwysocha@redhat.com: call folio_mapping() inside folio_needs_release()] Link: https://github.com/DaveWysochanskiRH/kernel/commit/902c990e311120179fa5de99d68364b2947b79ec Link: https://lkml.kernel.org/r/20230628104852.3391651-3-dhowells@redhat.com Fixes: 1f67e6d0b188 ("fscache: Provide a function to note the release of a page") Fixes: 047487c947e8 ("cachefiles: Implement the I/O routines") Signed-off-by: David Howells Signed-off-by: Dave Wysochanski Reported-by: Rohith Surabattula Suggested-by: Matthew Wilcox Tested-by: SeongJae Park Cc: Daire Byrne Cc: Matthew Wilcox Cc: Linus Torvalds Cc: Steve French Cc: Shyam Prasad N Cc: Rohith Surabattula Cc: Dave Wysochanski Cc: Dominique Martinet Cc: Ilya Dryomov Cc: Andreas Dilger Cc: Jingbo Xu Cc: "Theodore Ts'o" Cc: Xiubo Li Signed-off-by: Andrew Morton Stable-dep-of: 1898efcdbed3 ("block: update the stable_writes flag in bdev_add") Signed-off-by: Sasha Levin

cachefiles: use vfs_tmpfile_open() helper

2022-09-24T05:00:00+00:00

Use the vfs_tmpfile_open() helper instead of doing tmpfile creation and opening separately. The only minor difference is that previously no permission checking was done, while vfs_tmpfile_open() will call may_open() with zero access mask (i.e. no access is checked). Even if this would make a difference with callers caps (don't see how it could, even in the LSM codepaths) cachfiles raises caps before performing the tmpfile creation, so this extra permission check will not result in any regression. Reviewed-by: Christian Brauner (Microsoft) Signed-off-by: Miklos Szeredi

cachefiles: only pass inode to *mark_inode_inuse() helpers

2022-09-24T04:59:59+00:00

The only reason to pass dentry was because of a pr_notice() text. Move that to the two callers where it makes sense and add a WARN_ON() to the third. file_inode(file) is never NULL on an opened file. Remove check in cachefiles_unmark_inode_in_use(). Do not open code cachefiles_do_unmark_inode_in_use() in cachefiles_put_directory(). Signed-off-by: Miklos Szeredi

cachefiles: tmpfile error handling cleanup

2022-09-24T04:59:59+00:00

Separate the error labels from the success path and use 'ret' to store the error value before jumping to the error label. Signed-off-by: Miklos Szeredi

cachefiles: notify the user daemon when looking up cookie

2022-05-17T16:11:17+00:00

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: unmark inode in use in error path

2022-04-08T22:32:30+00:00

Unmark inode in use if error encountered. If the in-use flag leakage occurs in cachefiles_open_file(), Cachefiles will complain "Inode already in use" when later another cookie with the same index key is looked up. If the in-use flag leakage occurs in cachefiles_create_tmpfile(), though the "Inode already in use" warning won't be triggered, fix the leakage anyway. Reported-by: Gao Xiang Fixes: 1f08c925e7a3 ("cachefiles: Implement backing file wrangling") Signed-off-by: Jeffle Xu Signed-off-by: David Howells cc: linux-cachefs@redhat.com Link: https://listman.redhat.com/archives/linux-cachefs/2022-March/006615.html # v1 Link: https://listman.redhat.com/archives/linux-cachefs/2022-March/006618.html # v2

cachefiles: Trace active-mark failure

2022-01-21T21:36:28+00:00

Add a tracepoint to log failure to apply an active mark to a file in addition to tracing successfully setting and unsetting the mark. Also include the backing file inode number in the message logged to dmesg. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/164251404666.3435901.17331742792401482190.stgit@warthog.procyon.org.uk/ # v1

cachefiles: Make some tracepoint adjustments

2022-01-21T21:36:28+00:00

Make some adjustments to tracepoints to make the tracing a bit more followable: (1) Standardise on displaying the backing inode number as "B=" with no leading zeros. (2) Make the cachefiles_lookup tracepoint log the directory inode number as well as the looked-up inode number. (3) Add a cachefiles_lookup tracepoint into cachefiles_get_directory() to log directory lookup. (4) Add a new cachefiles_mkdir tracepoint and use that to log a successful mkdir from cachefiles_get_directory(). (5) Make the cachefiles_unlink and cachefiles_rename tracepoints log the inode number of the affected file/dir rather than dentry struct pointers. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/164251403694.3435901.9797725381831316715.stgit@warthog.procyon.org.uk/ # v1

fscache, cachefiles: Display stat of culling events

2022-01-07T13:43:18+00:00

Add a stat counter of culling events whereby the cache backend culls a file to make space (when asked by cachefilesd in this case) 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/163819654165.215744.3797804661644212436.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906961387.143852.9291157239960289090.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967168266.1823006.14436200166581605746.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021567619.640689.4339228906248763197.stgit@warthog.procyon.org.uk/ # v4