kernel/linux.git/fs/netfs/main.c, branch v6.12.91

netfs: Only create /proc/fs/netfs with CONFIG_PROC_FS

2025-05-02T05:59:26+00:00

[ Upstream commit 40cb48eba3b4b79e110c1a35d33a48cac54507a2 ] When testing a special config: CONFIG_NETFS_SUPPORTS=y CONFIG_PROC_FS=n The system crashes with something like: [ 3.766197] ------------[ cut here ]------------ [ 3.766484] kernel BUG at mm/mempool.c:560! [ 3.766789] Oops: invalid opcode: 0000 [#1] SMP NOPTI [ 3.767123] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Tainted: G W [ 3.767777] Tainted: [W]=WARN [ 3.767968] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), [ 3.768523] RIP: 0010:mempool_alloc_slab.cold+0x17/0x19 [ 3.768847] Code: 50 fe ff 58 5b 5d 41 5c 41 5d 41 5e 41 5f e9 93 95 13 00 [ 3.769977] RSP: 0018:ffffc90000013998 EFLAGS: 00010286 [ 3.770315] RAX: 000000000000002f RBX: ffff888100ba8640 RCX: 0000000000000000 [ 3.770749] RDX: 0000000000000000 RSI: 0000000000000003 RDI: 00000000ffffffff [ 3.771217] RBP: 0000000000092880 R08: 0000000000000000 R09: ffffc90000013828 [ 3.771664] R10: 0000000000000001 R11: 00000000ffffffea R12: 0000000000092cc0 [ 3.772117] R13: 0000000000000400 R14: ffff8881004b1620 R15: ffffea0004ef7e40 [ 3.772554] FS: 0000000000000000(0000) GS:ffff8881b5f3c000(0000) knlGS:0000000000000000 [ 3.773061] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 3.773443] CR2: ffffffff830901b4 CR3: 0000000004296001 CR4: 0000000000770ef0 [ 3.773884] PKRU: 55555554 [ 3.774058] Call Trace: [ 3.774232] [ 3.774371] mempool_alloc_noprof+0x6a/0x190 [ 3.774649] ? _printk+0x57/0x80 [ 3.774862] netfs_alloc_request+0x85/0x2ce [ 3.775147] netfs_readahead+0x28/0x170 [ 3.775395] read_pages+0x6c/0x350 [ 3.775623] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.775928] page_cache_ra_unbounded+0x1bd/0x2a0 [ 3.776247] filemap_get_pages+0x139/0x970 [ 3.776510] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.776820] filemap_read+0xf9/0x580 [ 3.777054] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.777368] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.777674] ? find_held_lock+0x32/0x90 [ 3.777929] ? netfs_start_io_read+0x19/0x70 [ 3.778221] ? netfs_start_io_read+0x19/0x70 [ 3.778489] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.778800] ? lock_acquired+0x1e6/0x450 [ 3.779054] ? srso_alias_return_thunk+0x5/0xfbef5 [ 3.779379] netfs_buffered_read_iter+0x57/0x80 [ 3.779670] __kernel_read+0x158/0x2c0 [ 3.779927] bprm_execve+0x300/0x7a0 [ 3.780185] kernel_execve+0x10c/0x140 [ 3.780423] ? __pfx_kernel_init+0x10/0x10 [ 3.780690] kernel_init+0xd5/0x150 [ 3.780910] ret_from_fork+0x2d/0x50 [ 3.781156] ? __pfx_kernel_init+0x10/0x10 [ 3.781414] ret_from_fork_asm+0x1a/0x30 [ 3.781677] [ 3.781823] Modules linked in: [ 3.782065] ---[ end trace 0000000000000000 ]--- This is caused by the following error path in netfs_init(): if (!proc_mkdir("fs/netfs", NULL)) goto error_proc; Fix this by adding ifdef in netfs_main(), so that /proc/fs/netfs is only created with CONFIG_PROC_FS. Signed-off-by: Song Liu Link: https://lore.kernel.org/20250409170015.2651829-1-song@kernel.org Acked-by: David Howells Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

Merge tag 'vfs-6.12.netfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-09-16T10:13:31+00:00

Pull netfs updates from Christian Brauner: "This contains the work to improve read/write performance for the new netfs library. The main performance enhancing changes are: - Define a structure, struct folio_queue, and a new iterator type, ITER_FOLIOQ, to hold a buffer as a replacement for ITER_XARRAY. See that patch for questions about naming and form. ITER_FOLIOQ is provided as a replacement for ITER_XARRAY. The problem with an xarray is that accessing it requires the use of a lock (typically the RCU read lock) - and this means that we can't supply iterate_and_advance() with a step function that might sleep (crypto for example) without having to drop the lock between pages. ITER_FOLIOQ is the iterator for a chain of folio_queue structs, where each folio_queue holds a small list of folios. A folio_queue struct is a simpler structure than xarray and is not subject to concurrent manipulation by the VM. folio_queue is used rather than a bvec[] as it can form lists of indefinite size, adding to one end and removing from the other on the fly. - Provide a copy_folio_from_iter() wrapper. - Make cifs RDMA support ITER_FOLIOQ. - Use folio queues in the write-side helpers instead of xarrays. - Add a function to reset the iterator in a subrequest. - Simplify the write-side helpers to use sheaves to skip gaps rather than trying to work out where gaps are. - In afs, make the read subrequests asynchronous, putting them into work items to allow the next patch to do progressive unlocking/reading. - Overhaul the read-side helpers to improve performance. - Fix the caching of a partial block at the end of a file. - Allow a store to be cancelled. Then some changes for cifs to make it use folio queues instead of xarrays for crypto bufferage: - Use raw iteration functions rather than manually coding iteration when hashing data. - Switch to using folio_queue for crypto buffers. - Remove the xarray bits. Make some adjustments to the /proc/fs/netfs/stats file such that: - All the netfs stats lines begin 'Netfs:' but change this to something a bit more useful. - Add a couple of stats counters to track the numbers of skips and waits on the per-inode writeback serialisation lock to make it easier to check for this as a source of performance loss. Miscellaneous work: - Ensure that the sb_writers lock is taken around vfs_{set,remove}xattr() in the cachefiles code. - Reduce the number of conditional branches in netfs_perform_write(). - Move the CIFS_INO_MODIFIED_ATTR flag to the netfs_inode struct and remove cifs_post_modify(). - Move the max_len/max_nr_segs members from netfs_io_subrequest to netfs_io_request as they're only needed for one subreq at a time. - Add an 'unknown' source value for tracing purposes. - Remove NETFS_COPY_TO_CACHE as it's no longer used. - Set the request work function up front at allocation time. - Use bh-disabling spinlocks for rreq->lock as cachefiles completion may be run from block-filesystem DIO completion in softirq context. - Remove fs/netfs/io.c" * tag 'vfs-6.12.netfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (25 commits) docs: filesystems: corrected grammar of netfs page cifs: Don't support ITER_XARRAY cifs: Switch crypto buffer to use a folio_queue rather than an xarray cifs: Use iterate_and_advance*() routines directly for hashing netfs: Cancel dirty folios that have no storage destination cachefiles, netfs: Fix write to partial block at EOF netfs: Remove fs/netfs/io.c netfs: Speed up buffered reading afs: Make read subreqs async netfs: Simplify the writeback code netfs: Provide an iterator-reset function netfs: Use new folio_queue data type and iterator instead of xarray iter cifs: Provide the capability to extract from ITER_FOLIOQ to RDMA SGEs iov_iter: Provide copy_folio_from_iter() mm: Define struct folio_queue and ITER_FOLIOQ to handle a sequence of folios netfs: Use bh-disabling spinlocks for rreq->lock netfs: Set the request work function upon allocation netfs: Remove NETFS_COPY_TO_CACHE netfs: Reserve netfs_sreq_source 0 as unset/unknown netfs: Move max_len/max_nr_segs from netfs_io_subrequest to netfs_io_stream ...

netfs: Speed up buffered reading

2024-09-12T10:20:41+00:00

Improve the efficiency of buffered reads in a number of ways: (1) Overhaul the algorithm in general so that it's a lot more compact and split the read submission code between buffered and unbuffered versions. The unbuffered version can be vastly simplified. (2) Read-result collection is handed off to a work queue rather than being done in the I/O thread. Multiple subrequests can be processes simultaneously. (3) When a subrequest is collected, any folios it fully spans are collected and "spare" data on either side is donated to either the previous or the next subrequest in the sequence. Notes: (*) Readahead expansion is massively slows down fio, presumably because it causes a load of extra allocations, both folio and xarray, up front before RPC requests can be transmitted. (*) RDMA with cifs does appear to work, both with SIW and RXE. (*) PG_private_2-based reading and copy-to-cache is split out into its own file and altered to use folio_queue. Note that the copy to the cache now creates a new write transaction against the cache and adds the folios to be copied into it. This allows it to use part of the writeback I/O code. Signed-off-by: David Howells cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-20-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner

netfs: Remove NETFS_COPY_TO_CACHE

2024-09-05T09:00:42+00:00

Remove NETFS_COPY_TO_CACHE as it isn't used anymore. Signed-off-by: David Howells cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-10-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner

netfs: Delete subtree of 'fs/netfs' when netfs module exits

2024-08-30T06:22:41+00:00

In netfs_init() or fscache_proc_init(), we create dentry under 'fs/netfs', but in netfs_exit(), we only delete the proc entry of 'fs/netfs' without deleting its subtree. This triggers the following WARNING: ================================================================== remove_proc_entry: removing non-empty directory 'fs/netfs', leaking at least 'requests' WARNING: CPU: 4 PID: 566 at fs/proc/generic.c:717 remove_proc_entry+0x160/0x1c0 Modules linked in: netfs(-) CPU: 4 UID: 0 PID: 566 Comm: rmmod Not tainted 6.11.0-rc3 #860 RIP: 0010:remove_proc_entry+0x160/0x1c0 Call Trace: netfs_exit+0x12/0x620 [netfs] __do_sys_delete_module.isra.0+0x14c/0x2e0 do_syscall_64+0x4b/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e ================================================================== Therefore use remove_proc_subtree() instead of remove_proc_entry() to fix the above problem. Fixes: 7eb5b3e3a0a5 ("netfs, fscache: Move /proc/fs/fscache to /proc/fs/netfs and put in a symlink") Cc: stable@kernel.org Signed-off-by: Baokun Li Link: https://lore.kernel.org/r/20240826113404.3214786-1-libaokun@huaweicloud.com Acked-by: David Howells Signed-off-by: Christian Brauner

netfs: Revert "netfs: Switch debug logging to pr_debug()"

2024-07-24T08:15:37+00:00

Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König cc: Christian Brauner cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs: Switch debug logging to pr_debug()

2024-06-12T12:25:41+00:00

Instead of inventing a custom way to conditionally enable debugging, just make use of pr_debug(), which also has dynamic debugging facilities and is more likely known to someone who hunts a problem in the netfs code. Also drop the module parameter netfs_debug which didn't have any effect without further source changes. (The variable netfs_debug was only used in #ifdef blocks for cpp vars that don't exist; Note that CONFIG_NETFS_DEBUG isn't settable via kconfig, a variable with that name never existed in the mainline and is probably just taken over (and renamed) from similar custom debug logging implementations.) Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Signed-off-by: Christian Brauner

netfs: Switch to using unsigned long long rather than loff_t

2024-05-01T17:07:35+00:00

Switch to using unsigned long long rather than loff_t in netfslib to avoid problems with the sign flipping in the maths when we're dealing with the byte at position 0x7fffffffffffffff. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: Ilya Dryomov cc: Xiubo Li cc: netfs@lists.linux.dev cc: ceph-devel@vger.kernel.org cc: linux-fsdevel@vger.kernel.org

netfs: Use mempools for allocating requests and subrequests

2024-05-01T17:07:35+00:00

Use mempools for allocating requests and subrequests in an effort to make sure that allocation always succeeds so that when performing writeback we can always make progress. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org

netfs: Remove ->launder_folio() support

2024-05-01T17:07:34+00:00

Remove support for ->launder_folio() from netfslib and expect filesystems to use filemap_invalidate_inode() instead. netfs_launder_folio() can then be got rid of. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: Eric Van Hensbergen cc: Latchesar Ionkov cc: Dominique Martinet cc: Christian Schoenebeck cc: David Howells cc: Marc Dionne cc: Steve French cc: Matthew Wilcox cc: linux-mm@kvack.org cc: linux-fsdevel@vger.kernel.org cc: netfs@lists.linux.dev cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: ceph-devel@vger.kernel.org cc: linux-cifs@vger.kernel.org cc: devel@lists.orangefs.org