kernel/linux.git/include/linux/nfs_fs.h, branch v6.18.21

NFS: Fix a deadlock involving nfs_release_folio()

2026-01-23T10:21:13+00:00

[ Upstream commit cce0be6eb4971456b703aaeafd571650d314bcca ] Wang Zhaolong reports a deadlock involving NFSv4.1 state recovery waiting on kthreadd, which is attempting to reclaim memory by calling nfs_release_folio(). The latter cannot make progress due to state recovery being needed. It seems that the only safe thing to do here is to kick off a writeback of the folio, without waiting for completion, or else kicking off an asynchronous commit. Reported-by: Wang Zhaolong Fixes: 96780ca55e3c ("NFS: fix up nfs_release_folio() to try to release the page") Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

nfs: Add timecreate to nfs inode

2025-07-14T22:20:02+00:00

Add tracking of the create time (a.k.a. btime) along with corresponding bitfields, request, and decode xdr routines. Signed-off-by: Anne Marie Merritt Signed-off-by: Lance Shelton Signed-off-by: Benjamin Coddington Reviewed-by: Jeff Layton Link: https://lore.kernel.org/r/1e3677b0655fa2bbaba0817b41d111d94a06e5ee.1748515333.git.bcodding@redhat.com Signed-off-by: Trond Myklebust

nfs: cache all open LOCALIO nfsd_file(s) in client

2025-01-14T22:04:05+00:00

This commit switches from leaning heavily on NFSD's filecache (in terms of GC'd nfsd_files) back to caching nfsd_files in the client. A later commit will add the callback mechanism needed to allow NFSD to force the NFS client to cleanup all cached nfsd_files. Add nfs_fh_localio_init() and 'struct nfs_fh_localio' to cache opened nfsd_file(s) (both a RO and RW nfsd_file is able to be opened and cached for a given nfs_fh). Update nfs_local_open_fh() to cache the nfsd_file once it is opened using __nfs_local_open_fh(). Introduce nfs_close_local_fh() to clear the cached open nfsd_files and call nfs_to_nfsd_file_put_local(). Refcounting is such that: - nfs_local_open_fh() is paired with nfs_close_local_fh(). - __nfs_local_open_fh() is paired with nfs_to_nfsd_file_put_local(). - nfs_local_file_get() is paired with nfs_local_file_put(). Signed-off-by: Mike Snitzer Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker

NFS: add atomic_open for NFSv3 to handle O_TRUNC correctly.

2024-05-20T15:09:20+00:00

With two clients, each with NFSv3 mounts of the same directory, the sequence: client1 client2 ls -l afile echo hello there > afile echo HELLO > afile cat afile will show HELLO there because the O_TRUNC requested in the final 'echo' doesn't take effect. This is because the "Negative dentry, just create a file" section in lookup_open() assumes that the file *does* get created since the dentry was negative, so it sets FMODE_CREATED, and this causes do_open() to clear O_TRUNC and so the file doesn't get truncated. Even mounting with -o lookupcache=none does not help as nfs_neg_need_reval() always returns false if LOOKUP_CREATE is set. This patch fixes the problem by providing an atomic_open inode operation for NFSv3 (and v2). The code is largely the code from the branch in lookup_open() when atomic_open is not provided. The significant change is that the O_TRUNC flag is passed a new nfs_do_create() which add 'trunc' handling to nfs_create(). With this change we also optimise away an unnecessary LOOKUP before the file is created. Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust

nfs: fix UAF in direct writes

2024-03-09T14:14:51+00:00

In production we have been hitting the following warning consistently ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 17 PID: 1800359 at lib/refcount.c:28 refcount_warn_saturate+0x9c/0xe0 Workqueue: nfsiod nfs_direct_write_schedule_work [nfs] RIP: 0010:refcount_warn_saturate+0x9c/0xe0 PKRU: 55555554 Call Trace: ? __warn+0x9f/0x130 ? refcount_warn_saturate+0x9c/0xe0 ? report_bug+0xcc/0x150 ? handle_bug+0x3d/0x70 ? exc_invalid_op+0x16/0x40 ? asm_exc_invalid_op+0x16/0x20 ? refcount_warn_saturate+0x9c/0xe0 nfs_direct_write_schedule_work+0x237/0x250 [nfs] process_one_work+0x12f/0x4a0 worker_thread+0x14e/0x3b0 ? ZSTD_getCParams_internal+0x220/0x220 kthread+0xdc/0x120 ? __btf_name_valid+0xa0/0xa0 ret_from_fork+0x1f/0x30 This is because we're completing the nfs_direct_request twice in a row. The source of this is when we have our commit requests to submit, we process them and send them off, and then in the completion path for the commit requests we have if (nfs_commit_end(cinfo.mds)) nfs_direct_write_complete(dreq); However since we're submitting asynchronous requests we sometimes have one that completes before we submit the next one, so we end up calling complete on the nfs_direct_request twice. The only other place we use nfs_generic_commit_list() is in __nfs_commit_inode, which wraps this call in a nfs_commit_begin(); nfs_commit_end(); Which is a common pattern for this style of completion handling, one that is also repeated in the direct code with get_dreq()/put_dreq() calls around where we process events as well as in the completion paths. Fix this by using the same pattern for the commit requests. Before with my 200 node rocksdb stress running this warning would pop every 10ish minutes. With my patch the stress test has been running for several hours without popping. Signed-off-by: Josef Bacik Cc: stable@vger.kernel.org Signed-off-by: Trond Myklebust

nfs: Remove writepage

2024-01-04T15:47:56+00:00

NFS already has writepages and migrate_folio, so it does not need to implement writepage. The writepage operation is deprecated as it leads to worse performance under high memory pressure due to folios being written out in LRU order rather than sequentially within a file. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Anna Schumaker

NFSv3: handle out-of-order write replies.

2023-04-11T20:13:21+00:00

NFSv3 includes pre/post wcc attributes which allow the client to determine if all changes to the file have been made by the client itself, or if any might have been made by some other client. If there are gaps in the pre/post ctime sequence it must be assumed that some other client changed the file in that gap and the local cache must be suspect. The next time the file is opened the cache should be invalidated. Since Commit 1c341b777501 ("NFS: Add deferred cache invalidation for close-to-open consistency violations") in linux 5.3 the Linux client has been triggering this invalidation. The chunk in nfs_update_inode() in particularly triggers. Unfortunately Linux NFS assumes that all replies will be processed in the order sent, and will arrive in the order processed. This is not true in general. Consequently Linux NFS might ignore the wcc info in a WRITE reply because the reply is in response to a WRITE that was sent before some other request for which a reply has already been seen. This is detected by Linux using the gencount tests in nfs_inode_attr_cmp(). Also, when the gencount tests pass it is still possible that the request were processed on the server in a different order, and a gap seen in the ctime sequence might be filled in by a subsequent reply, so gaps should not immediately trigger delayed invalidation. The net result is that writing to a server and then reading the file back can result in going to the server for the read rather than serving it from cache - all because a couple of replies arrived out-of-order. This is a performance regression over kernels before 5.3, though the change in 5.3 is a correctness improvement. This has been seen with Linux writing to a Netapp server which occasionally re-orders requests. In testing the majority of requests were in-order, but a few (maybe 2 or three at a time) could be re-ordered. This patch addresses the problem by recording any gaps seen in the pre/post ctime sequence and not triggering invalidation until either there are too many gaps to fit in the table, or until there are no more active writes and the remaining gaps cannot be resolved. We allocate a table of 16 gaps on demand. If the allocation fails we revert to current behaviour which is of little cost as we are unlikely to be able to cache the writes anyway. In the table we store "start->end" pair when iversion is updated and "end<-start" pairs pre/post pairs reported by the server. Usually these exactly cancel out and so nothing is stored. When there are out-of-order replies we do store gaps and these will eventually be cancelled against later replies when this client is the only writer. If the final write is out-of-order there may be one gap remaining when the file is closed. This will be noticed and if there is precisely on gap and if the iversion can be advanced to match it, then we do so. This patch makes no attempt to handle directories correctly. The same problem potentially exists in the out-of-order replies to create/unlink requests can cause future lookup requires to be sent to the server unnecessarily. A similar scheme using the same primitives could be used to notice and handle out-of-order replies. Signed-off-by: NeilBrown Signed-off-by: Anna Schumaker

NFS: Remove fscache specific trace points and NFS_INO_FSCACHE bit

2023-04-11T17:08:27+00:00

The NFS specific trace points are no longer needed as tracing is well covered by netfs and fscache. Signed-off-by: Dave Wysochanski Reviewed-by: Jeff Layton Tested-by: Daire Byrne Signed-off-by: Anna Schumaker

NFS: Configure support for netfs when NFS fscache is configured

2023-04-11T17:00:02+00:00

As first steps for support of the netfs library when NFS_FSCACHE is configured, add NETFS_SUPPORT to Kconfig and add the required netfs_inode into struct nfs_inode. Using netfs requires we move the VFS inode structure to be stored inside struct netfs_inode, along with the fscache_cookie. Thus, if NFS_FSCACHE is configured, place netfs_inode inside an anonymous union so the vfs_inode memory is the same and we do not need to modify other non-fscache areas of NFS. In addition, inside the NFS fscache code, use the new helpers, netfs_inode() and netfs_i_cookie() helpers, and remove our own helper, nfs_i_fscache(). Later patches will convert NFS fscache to fully use netfs. Signed-off-by: Dave Wysochanski Tested-by: Daire Byrne Signed-off-by: Anna Schumaker

Merge tag 'nfs-for-6.3-1' of git://git.linux-nfs.org/projects/anna/linux-nfs

2023-02-22T22:47:20+00:00

Pull NFS client updates from Anna Schumaker: "New Features: - Convert the read and write paths to use folios Bugfixes and Cleanups: - Fix tracepoint state manager flag printing - Fix disabling swap files - Fix NFSv4 client identifier sysfs path in the documentation - Don't clear NFS_CAP_COPY if server returns NFS4ERR_OFFLOAD_DENIED - Treat GETDEVICEINFO errors as a layout failure - Replace kmap_atomic() calls with kmap_local_page() - Constify sunrpc sysfs kobj_type structures" * tag 'nfs-for-6.3-1' of git://git.linux-nfs.org/projects/anna/linux-nfs: (25 commits) fs/nfs: Replace kmap_atomic() with kmap_local_page() in dir.c pNFS/filelayout: treat GETDEVICEINFO errors as layout failure Documentation: Fix sysfs path for the NFSv4 client identifier nfs42: do not fail with EIO if ssc returns NFS4ERR_OFFLOAD_DENIED NFS: fix disabling of swap SUNRPC: make kobj_type structures constant nfs4trace: fix state manager flag printing NFS: Remove unnecessary check in nfs_read_folio() NFS: Improve tracing of nfs_wb_folio() NFS: Enable tracing of nfs_invalidate_folio() and nfs_launder_folio() NFS: fix up nfs_release_folio() to try to release the page NFS: Clean up O_DIRECT request allocation NFS: Fix up nfs_vm_page_mkwrite() for folios NFS: Convert nfs_write_begin/end to use folios NFS: Remove unused function nfs_wb_page() NFS: Convert buffered writes to use folios NFS: Convert the function nfs_wb_page() to use folios NFS: Convert buffered reads to use folios NFS: Add a helper nfs_wb_folio() NFS: Convert the remaining pagelist helper functions to support folios ...