kernel/linux.git/fs/nfs, branch v7.1.8

NFS: Charge unstable writes by request size, not folio size

2026-07-24T14:21:08+00:00

commit 27934d02cbeb8a957dd11c985a579e58d30c5270 upstream. nfs_folio_mark_unstable() and nfs_folio_clear_commit() charge and uncharge NR_WRITEBACK/WB_WRITEBACK by folio_nr_pages(folio) once per *request* added to or removed from a commit list. This is correct only when a folio has a single associated request. When pg_test splits a folio into N sub-folio requests (e.g. pNFS flexfiles striping with a stripe unit smaller than the folio size, or plain wsize-limited splitting), each of the N requests independently charges the whole folio's page count, inflating the accounting by a factor of N per folio. With large folios and small stripe units this reaches multiple orders of magnitude: a 2 MiB folio split into 512 4 KiB requests can charge up to 512x its real size, pushing global dirty+writeback accounting past the system's dirty threshold and forcing every buffered writer on the host into the hard-throttle path, including unrelated in-kernel NFS server threads sharing the box. Charge each request only for the pages it actually covers. Fixes: 0c493b5cf16e ("NFS: Convert buffered writes to use folios") Cc: stable@vger.kernel.org Signed-off-by: Benjamin Coddington Assisted-By: Claude Sonnet 5 Signed-off-by: Anna Schumaker Signed-off-by: Greg Kroah-Hartman

nfs: use nfsi->rwsem to protect traversal of the file lock list

2026-07-24T14:20:08+00:00

[ Upstream commit 4837fb36219e6c08b666bc31a86841bad8526358 ] Lingfeng identified a bug and suggested two solutions, but both appear to have issues. Generally, we cannot release flc_lock while iterating over the file lock list to avoid use-after-free (UAF) problems with file locks. However, functions like nfs_delegation_claim_locks and nfs4_reclaim_locks cannot adhere to this rule because recover_lock or nfs4_lock_delegation_recall may take a long time. To resolve this, NFS switches to using nfsi->rwsem for the same protection, and nfs_reclaim_locks follows this approach. Although nfs_delegation_claim_locks uses so_delegreturn_mutex instead, this is inadequate since a single inode can have multiple nfs4_state instances. Therefore, the fix is to also use nfsi->rwsem in this case. Furthermore, after commit c69899a17ca4 ("NFSv4: Update of VFS byte range lock must be atomic with the stateid update"), the functions nfs4_locku_done and nfs4_lock_done also break this rule because they call locks_lock_inode_wait without holding nfsi->rwsem. Simply adding this protection could cause many deadlocks, so instead, the call to locks_lock_inode_wait is moved into _nfs4_proc_setlk. Regarding the bug fixed by commit c69899a17ca4 ("NFSv4: Update of VFS byte range lock must be atomic with the stateid update"), it has been resolved after commit 0460253913e5 ("NFSv4: nfs4_do_open() is incorrectly triggering state recovery") because all slots are drained before calling nfs4_do_reclaim, which prevents concurrent stateid changes along this path. Also, nfs_delegation_claim_locks does not cause this concurrency either since when _nfs4_proc_setlk is called with NFS_DELEGATED_STATE, no RPC is sent, so nfs4_lock_done is not called. Therefore, nfs4_lock_delegation_recall from nfs_delegation_claim_locks is the first time the stateid is set. Reported-by: Li Lingfeng Closes: https://lore.kernel.org/all/20250419085709.1452492-1-lilingfeng3@huawei.com/ Closes: https://lore.kernel.org/all/20250715030559.2906634-1-lilingfeng3@huawei.com/ Fixes: c69899a17ca4 ("NFSv4: Update of VFS byte range lock must be atomic with the stateid update") Signed-off-by: Yang Erkun Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin

NFSv4/flexfiles: honor FF_FLAGS_NO_IO_THRU_MDS in pg_get_mirror_count_write

2026-07-24T14:20:07+00:00

[ Upstream commit 1d62e659c0bf11649cf48e002c2a55d148f2610a ] The FF_FLAGS_NO_IO_THRU_MDS flag lives on each lseg, so any fallback decision made when there is no current lseg (e.g. between LAYOUTRETURN and the next LAYOUTGET) cannot run the per-lseg check. Introduce a sticky hdr-level ditto for FF_FLAGS_NO_IO_THRU_MDS in struct nfs4_flexfile_layout::flags (NFS4_FF_HDR_NO_IO_THRU_MDS bit), set whenever ff_layout_alloc_lseg() parses an lseg with the flag. The bit is never cleared for the lifetime of the layout hdr; the server is assumed to be consistent in its no-fallback policy per file. kzalloc() in ff_layout_alloc_layout_hdr() zero-initializes the field. Use the new ff_layout_hdr_no_fallback_to_mds() helper to gate ff_layout_pg_get_mirror_count_write(): when pnfs_update_layout() returns NULL (e.g. NFS_LAYOUT_BULK_RECALL, pnfs_layout_io_test_failed, pnfs_layoutgets_blocked) the existing code unconditionally calls nfs_pageio_reset_write_mds(). This is a source of unwanted WRITE to MDS. Fix it by checking NFS4_FF_HDR_NO_IO_THRU_MDS bit, and if set surface -EAGAIN instead; the writepage-side caller (nfs_do_writepage() for buffered, nfs_direct_write_reschedule() for O_DIRECT) then redirties the request so writeback retries via pNFS. Fixes: 260074cd8413 ("pNFS/flexfiles: Add support for FF_FLAGS_NO_IO_THRU_MDS") Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Mike Snitzer Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin

NFSv4/flexfiles: honor FF_FLAGS_NO_IO_THRU_MDS on fatal DS connect errors

2026-07-24T14:20:07+00:00

[ Upstream commit 7a375cafc14ed151508f908ea5681caf0a9cc1d6 ] Commit f06bedfa62d5 ("pNFS/flexfiles: don't attempt pnfs on fatal DS errors") teaches ff_layout_{read,write}_pagelist() to return PNFS_NOT_ATTEMPTED when nfs4_ff_layout_prepare_ds() fails with a nfs_error_is_fatal() errno (e.g. -ETIMEDOUT from a SOFTCONN connect deadline, -ENOMEM, -ERESTARTSYS), so that the client gives up instead of spinning. pnfs_do_{read,write}() then dispatches the I/O through pnfs_{read,write}_through_mds() → nfs_pageio_reset_{read,write}_mds(). That fallback is unconditional and silently violates FF_FLAGS_NO_IO_THRU_MDS: when the layout segment carries the flag (typically single-mirror appliance layouts where MDS I/O is explicitly forbidden), the out_failed: path's \`&& !ds_fatal_error\` clause overrides the flag's short-circuit through ff_layout_avoid_mds_available_ds() and routes the I/O to the MDS file handle anyway. This is reachable in practice during a data-server restart: SOFTCONN exhaustion produces -ETIMEDOUT, which is fatal per nfs_error_is_fatal(), which triggers PNFS_NOT_ATTEMPTED, which silently goes to MDS. Preserve the upstream "don't spin on fatal errors" intent for layouts that permit MDS fallback. For layouts with FF_FLAGS_NO_IO_THRU_MDS set, mark the layout for return and request PNFS_TRY_AGAIN instead; if the server cannot supply a usable layout the failure now surfaces cleanly via pnfs_update_layout(), rather than via silent MDS I/O that contradicts the flag. Fixes: f06bedfa62d5 ("pNFS/flexfiles: don't attempt pnfs on fatal DS errors") Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Mike Snitzer Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin

nfs: keep PG_UPTODATE clear after read errors in page groups

2026-07-24T14:20:07+00:00

[ Upstream commit 3ff72e1cdf5c337b6acfcf3fcef748c5b9a5316b ] When a read request is split into multiple subrequests, earlier completions may advance PG_UPTODATE state for the page group once their bytes fall within hdr->good_bytes. If a later subrequest in the same group then completes with NFS_IOHDR_ERROR, the read path needs to clear any accumulated PG_UPTODATE state and keep later completions from rebuilding it. Otherwise, a subsequent successful subrequest can re-enter nfs_page_group_set_uptodate(), restore the page-group sync state, and leave stale PG_UPTODATE behind for nfs_page_group_destroy() to trip over in nfs_free_request(). Add a sticky page-group read-failed flag. Once any subrequest in the group is known to be bad, mark the group failed, clear any accumulated PG_UPTODATE state, and refuse further PG_UPTODATE synchronization for the rest of the completion walk. Fixes: 67d0338edd71 ("nfs: page group syncing in read path") Signed-off-by: Clark Wang Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin

NFSv4/pnfs: defer return_range callbacks until after inode unlock

2026-07-24T14:20:07+00:00

[ Upstream commit 77b160b2d863d37f36b6c38e80a7d259ce939e69 ] Sometimes unmounting an NFS filesystem mounted with pNFS SCSI layouts triggers the following warning: BUG: scheduling while atomic: umount.nfs4/... __schedule_bug+0xbd/0x100 schedule_debug.constprop.0+0x19f/0x220 __schedule+0x10d/0x10a0 schedule+0x74/0x190 schedule_timeout+0xf5/0x220 io_schedule_timeout+0xd5/0x160 __wait_for_common+0x186/0x4b0 blk_execute_rq+0x2ef/0x3a0 scsi_execute_cmd+0x1ff/0x700 sd_pr_out_command.isra.0+0x242/0x380 [sd_mod] bl_unregister_scsi.constprop.0+0x109/0x3c0 [blocklayoutdriver] bl_unregister_dev+0x175/0x1c0 [blocklayoutdriver] bl_free_device+0x1f/0x1b0 [blocklayoutdriver] bl_free_deviceid_node+0x12/0x30 [blocklayoutdriver] nfs4_put_deviceid_node+0x171/0x360 [nfsv4] ext_tree_remove+0x11c/0x1d0 [blocklayoutdriver] _pnfs_return_layout+0x416/0x900 [nfsv4] nfs4_evict_inode+0x108/0x130 [nfsv4] evict+0x316/0x750 dispose_list+0xf1/0x1a0 evict_inodes+0x33f/0x440 generic_shutdown_super+0xc9/0x4e0 kill_anon_super+0x3a/0x90 nfs_kill_super+0x44/0x60 [nfs] deactivate_locked_super+0xb8/0x1b0 cleanup_mnt+0x25a/0x380 task_work_run+0x13e/0x210 exit_to_user_mode_loop+0x169/0x400 do_syscall_64+0x467/0x1550 entry_SYSCALL_64_after_hwframe+0x76/0x7e The warning occurs because the block layout driver unregisters the SCSI device while the inode lock is still held. Device unregistration issues a SCSI PR command, which may sleep, resulting in a "scheduling while atomic" warning. During layout return, ext_tree_remove() invokes the layout driver's return_range callback while holding the inode lock. For block layouts, this callback eventually calls bl_unregister_scsi(), which may block in scsi_execute_cmd() while issuing PR commands to the device. Fix this by deferring the return_range callbacks until after the inode lock has been released. The layout header reference count is incremented before invoking return_range(), ensuring that the layout header remains valid while the layout driver removes extents from the extent tree. Fixes: c88953d87f5c8 ("pnfs: add return_range method") Signed-off-by: Dai Ngo Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin

pNFS/filelayout: fix cheking if a layout is striped

2026-07-24T14:20:07+00:00

[ Upstream commit 91668417d4e925c98cae4a55b1b9860380ddbf16 ] A layout can still be striped with num_fh = 1 as it is perfectly possible that both MDS and DSs can handle the same filehandle. Hence check according to stripe_count > 1, which is the correct check to begin with. We should not be called with flseg->dsaddr = NULL, but if for some reason we do, return our best guess with is flseg->num_fh > 1. Fixes: a6b9d2fa0024 ("pNFS/filelayout: Fix coalescing test for single DS") Signed-off-by: Sagi Grimberg Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin

vfs: add FS_USERNS_DELEGATABLE flag and set it for NFS

2026-07-24T14:19:41+00:00

[ Upstream commit c5d6cac28646b0d5d81ef632be748ae93c1f36c7 ] Commit e1c5ae59c0f2 ("fs: don't allow non-init s_user_ns for filesystems without FS_USERNS_MOUNT") prevents the mount of any filesystem inside a container that doesn't have FS_USERNS_MOUNT set. This broke NFS mounts in our containerized environment. We have a daemon somewhat like systemd-mountfsd running in the init_ns. A process does a fsopen() inside the container and passes it to the daemon via unix socket. The daemon then vets that the request is for an allowed NFS server and performs the mount. This now fails because the fc->user_ns is set to the value in the container and NFS doesn't set FS_USERNS_MOUNT. We don't want to add FS_USERNS_MOUNT to NFS since that would allow the container to mount any NFS server (even malicious ones). Add a new FS_USERNS_DELEGATABLE flag, and enable it on NFS. Fixes: e1c5ae59c0f2 ("fs: don't allow non-init s_user_ns for filesystems without FS_USERNS_MOUNT") Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260129-twmount-v1-1-4874ed2a15c4@kernel.org Acked-by: Anna Schumaker Reviewed-by: Alexander Mikhalitsyn Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Sasha Levin

NFSv4: include MAY_WRITE in open permission mask for O_TRUNC

2026-07-18T14:55:44+00:00

commit 5140f099ecd8a2f2808b7f7b720ee1bad8468974 upstream. POSIX requires write permission to truncate a file, so an open() that specifies O_TRUNC must be authorized for write access regardless of the O_ACCMODE access mode. nfs_open_permission_mask() builds the access mask passed to nfs_may_open(), which is the local authorization gate for OPENs the client serves itself from a cached write delegation via the can_open_delegated() path in nfs4_try_open_cached(). The mask is derived from O_ACCMODE alone, so an open(O_RDONLY | O_TRUNC) against a file the caller cannot write requests only MAY_READ and passes the local check. The OPEN is then satisfied locally and the truncation is issued to the server as a SETATTR(size=0) over the delegation stateid, which the server accepts under standard write-delegation semantics. POSIX requires that this open fail with EACCES. Include MAY_WRITE in the mask whenever O_TRUNC is set so the local check matches the access the server would have enforced. Suggested-by: Trond Myklebust Fixes: af22f94ae02a ("NFSv4: Simplify _nfs4_do_access()") Cc: stable@vger.kernel.org Signed-off-by: Benjamin Coddington Signed-off-by: Anna Schumaker Signed-off-by: Greg Kroah-Hartman

NFS: Prevent resource leak in nfs_alloc_server()

2026-07-04T11:45:09+00:00

commit d189f224308c8ac3feeea8e442c99922bd18f1b2 upstream. It was overlooked to call ida_free() after a failed nfs_alloc_iostats() call. Thus add the missed function call in an if branch. Fixes: 1c7251187dc067a6d460cf33ca67da9c1dd87807 ("NFS: add superblock sysfs entries") Cc: stable@vger.kernel.org Reported-by: Christophe Jaillet Closes: https://lore.kernel.org/linux-nfs/1c8e10c9-def7-4f0d-8aa1-23c8035a38c8@wanadoo.fr/ Signed-off-by: Markus Elfring Signed-off-by: Anna Schumaker Signed-off-by: Greg Kroah-Hartman