kernel/linux.git/fs/ceph/addr.c, branch v6.19.11

ceph: do not skip the first folio of the next object in writeback

2026-03-19T15:15:07+00:00

commit 081a0b78ef30f5746cda3e92e28b4d4ae92901d1 upstream. When `ceph_process_folio_batch` encounters a folio past the end of the current object, it should leave it in the batch so that it is picked up in the next iteration. Removing the folio from the batch means that it does not get written back and remains dirty instead. This makes `fsync()` silently skip some of the data, delays capability release, and breaks coherence with `O_DIRECT`. The link below contains instructions for reproducing the bug. Cc: stable@vger.kernel.org Fixes: ce80b76dd327 ("ceph: introduce ceph_process_folio_batch() method") Link: https://tracker.ceph.com/issues/75156 Signed-off-by: Hristo Venev Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman

ceph: fix write storm on fscrypted files

2026-03-04T12:21:39+00:00

[ Upstream commit cac190c7674fea71620d754ffcdaaeed7c551dbc ] CephFS stores file data across multiple RADOS objects. An object is the atomic unit of storage, so the writeback code must clean only folios that belong to the same object with each OSD request. CephFS also supports RAID0-style striping of file contents: if enabled, each object stores multiple unbroken "stripe units" covering different portions of the file; if disabled, a "stripe unit" is simply the whole object. The stripe unit is (usually) reported as the inode's block size. Though the writeback logic could, in principle, lock all dirty folios belonging to the same object, its current design is to lock only a single stripe unit at a time. Ever since this code was first written, it has determined this size by checking the inode's block size. However, the relatively-new fscrypt support needed to reduce the block size for encrypted inodes to the crypto block size (see 'fixes' commit), which causes an unnecessarily high number of write operations (~1024x as many, with 4MiB objects) and correspondingly degraded performance. Fix this (and clarify intent) by using i_layout.stripe_unit directly in ceph_define_write_size() so that encrypted inodes are written back with the same number of operations as if they were unencrypted. This patch depends on the preceding commit ("ceph: do not propagate page array emplacement errors as batch errors") for correctness. While it applies cleanly on its own, applying it alone will introduce a regression. This dependency is only relevant for kernels where ce80b76dd327 ("ceph: introduce ceph_process_folio_batch() method") has been applied; stable kernels without that commit are unaffected. Cc: stable@vger.kernel.org Fixes: 94af0470924c ("ceph: add some fscrypt guardrails") Signed-off-by: Sam Edwards Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin

ceph: do not propagate page array emplacement errors as batch errors

2026-03-04T12:21:39+00:00

[ Upstream commit 707104682e3c163f7c14cdd6b07a3e95fb374759 ] When fscrypt is enabled, move_dirty_folio_in_page_array() may fail because it needs to allocate bounce buffers to store the encrypted versions of each folio. Each folio beyond the first allocates its bounce buffer with GFP_NOWAIT. Failures are common (and expected) under this allocation mode; they should flush (not abort) the batch. However, ceph_process_folio_batch() uses the same `rc` variable for its own return code and for capturing the return codes of its routine calls; failing to reset `rc` back to 0 results in the error being propagated out to the main writeback loop, which cannot actually tolerate any errors here: once `ceph_wbc.pages` is allocated, it must be passed to ceph_submit_write() to be freed. If it survives until the next iteration (e.g. due to the goto being followed), ceph_allocate_page_array()'s BUG_ON() will oops the worker. Note that this failure mode is currently masked due to another bug (addressed next in this series) that prevents multiple encrypted folios from being selected for the same write. For now, just reset `rc` when redirtying the folio to prevent errors in move_dirty_folio_in_page_array() from propagating. Note that move_dirty_folio_in_page_array() is careful never to return errors on the first folio, so there is no need to check for that. After this change, ceph_process_folio_batch() no longer returns errors; its only remaining failure indicator is `locked_pages == 0`, which the caller already handles correctly. Cc: stable@vger.kernel.org Fixes: ce80b76dd327 ("ceph: introduce ceph_process_folio_batch() method") Signed-off-by: Sam Edwards Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin

ceph: supply snapshot context in ceph_uninline_data()

2026-03-04T12:20:45+00:00

[ Upstream commit 305ff6b3a03c230d3c07b61457e961406d979693 ] The ceph_uninline_data function was missing proper snapshot context handling for its OSD write operations. Both CEPH_OSD_OP_CREATE and CEPH_OSD_OP_WRITE requests were passing NULL instead of the appropriate snapshot context, which could lead to unnecessary object clone. Reproducer: ../src/vstart.sh --new -x --localhost --bluestore // turn on cephfs inline data ./bin/ceph fs set a inline_data true --yes-i-really-really-mean-it // allow fs_a client to take snapshot ./bin/ceph auth caps client.fs_a mds 'allow rwps fsname=a' mon 'allow r fsname=a' osd 'allow rw tag cephfs data=a' // mount cephfs with fuse, since kernel cephfs doesn't support inline write ceph-fuse --id fs_a -m 127.0.0.1:40318 --conf ceph.conf -d /mnt/mycephfs/ // bump snapshot seq mkdir /mnt/mycephfs/.snap/snap1 echo "foo" > /mnt/mycephfs/test // umount and mount it again using kernel cephfs client umount /mnt/mycephfs mount -t ceph fs_a@.a=/ /mnt/mycephfs/ -o conf=./ceph.conf echo "bar" >> /mnt/mycephfs/test ./bin/rados listsnaps -p cephfs.a.data $(printf "%x\n" $(stat -c %i /mnt/mycephfs/test)).00000000 will see this object does unnecessary clone 1000000000a.00000000 (seq:2): cloneid snaps size overlap 2 2 4 [] head - 8 but it's expected to see 10000000000.00000000 (seq:2): cloneid snaps size overlap head - 8 since there's no snapshot between these 2 writes clone happened because the first osd request CEPH_OSD_OP_CREATE doesn't pass snap context so object is created with snap seq 0, but later data writeback is equipped with snapshot context. snap.seq(1) > object snap seq(0), so osd does object clone. This fix properly acquiring the snapshot context before performing write operations. Signed-off-by: ethanwu Reviewed-by: Viacheslav Dubeyko Tested-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin

fs: Make wbc_to_tag() inline and use it in fs.

2025-10-29T22:33:48+00:00

The logic in wbc_to_tag() is widely used in file systems, so modify this function to be inline and use it in file systems. This patch has only passed compilation tests, but it should be fine. Signed-off-by: Julian Sun Reviewed-by: Qu Wenruo Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

ceph: fix crash after fscrypt_encrypt_pagecache_blocks() error

2025-09-09T10:57:03+00:00

The function move_dirty_folio_in_page_array() was created by commit ce80b76dd327 ("ceph: introduce ceph_process_folio_batch() method") by moving code from ceph_writepages_start() to this function. This new function is supposed to return an error code which is checked by the caller (now ceph_process_folio_batch()), and on error, the caller invokes redirty_page_for_writepage() and then breaks from the loop. However, the refactoring commit has gone wrong, and it by accident, it always returns 0 (= success) because it first NULLs the pointer and then returns PTR_ERR(NULL) which is always 0. This means errors are silently ignored, leaving NULL entries in the page array, which may later crash the kernel. The simple solution is to call PTR_ERR() before clearing the pointer. Cc: stable@vger.kernel.org Fixes: ce80b76dd327 ("ceph: introduce ceph_process_folio_batch() method") Link: https://lore.kernel.org/ceph-devel/aK4v548CId5GIKG1@swift.blarg.de/ Signed-off-by: Max Kellermann Reviewed-by: Ilya Dryomov Signed-off-by: Ilya Dryomov

ceph: always call ceph_shift_unused_folios_left()

2025-09-09T10:57:02+00:00

The function ceph_process_folio_batch() sets folio_batch entries to NULL, which is an illegal state. Before folio_batch_release() crashes due to this API violation, the function ceph_shift_unused_folios_left() is supposed to remove those NULLs from the array. However, since commit ce80b76dd327 ("ceph: introduce ceph_process_folio_batch() method"), this shifting doesn't happen anymore because the "for" loop got moved to ceph_process_folio_batch(), and now the `i` variable that remains in ceph_writepages_start() doesn't get incremented anymore, making the shifting effectively unreachable much of the time. Later, commit 1551ec61dc55 ("ceph: introduce ceph_submit_write() method") added more preconditions for doing the shift, replacing the `i` check (with something that is still just as broken): - if ceph_process_folio_batch() fails, shifting never happens - if ceph_move_dirty_page_in_page_array() was never called (because ceph_process_folio_batch() has returned early for some of various reasons), shifting never happens - if `processed_in_fbatch` is zero (because ceph_process_folio_batch() has returned early for some of the reasons mentioned above or because ceph_move_dirty_page_in_page_array() has failed), shifting never happens Since those two commits, any problem in ceph_process_folio_batch() could crash the kernel, e.g. this way: BUG: kernel NULL pointer dereference, address: 0000000000000034 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: Oops: 0002 [#1] SMP NOPTI CPU: 172 UID: 0 PID: 2342707 Comm: kworker/u778:8 Not tainted 6.15.10-cm4all1-es #714 NONE Hardware name: Dell Inc. PowerEdge R7615/0G9DHV, BIOS 1.6.10 12/08/2023 Workqueue: writeback wb_workfn (flush-ceph-1) RIP: 0010:folios_put_refs+0x85/0x140 Code: 83 c5 01 39 e8 7e 76 48 63 c5 49 8b 5c c4 08 b8 01 00 00 00 4d 85 ed 74 05 41 8b 44 ad 00 48 8b 15 b0 > RSP: 0018:ffffb880af8db778 EFLAGS: 00010207 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000003 RDX: ffffe377cc3b0000 RSI: 0000000000000000 RDI: ffffb880af8db8c0 RBP: 0000000000000000 R08: 000000000000007d R09: 000000000102b86f R10: 0000000000000001 R11: 00000000000000ac R12: ffffb880af8db8c0 R13: 0000000000000000 R14: 0000000000000000 R15: ffff9bd262c97000 FS: 0000000000000000(0000) GS:ffff9c8efc303000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000034 CR3: 0000000160958004 CR4: 0000000000770ef0 PKRU: 55555554 Call Trace: ceph_writepages_start+0xeb9/0x1410 The crash can be reproduced easily by changing the ceph_check_page_before_write() return value to `-E2BIG`. (Interestingly, the crash happens only if `huge_zero_folio` has already been allocated; without `huge_zero_folio`, is_huge_zero_folio(NULL) returns true and folios_put_refs() skips NULL entries instead of dereferencing them. That makes reproducing the bug somewhat unreliable. See https://lore.kernel.org/20250826231626.218675-1-max.kellermann@ionos.com for a discussion of this detail.) My suggestion is to move the ceph_shift_unused_folios_left() to right after ceph_process_folio_batch() to ensure it always gets called to fix up the illegal folio_batch state. Cc: stable@vger.kernel.org Fixes: ce80b76dd327 ("ceph: introduce ceph_process_folio_batch() method") Link: https://lore.kernel.org/ceph-devel/aK4v548CId5GIKG1@swift.blarg.de/ Signed-off-by: Max Kellermann Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov

Merge tag 'vfs-6.17-rc1.mmap_prepare' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-07-28T20:43:25+00:00

Pull mmap_prepare updates from Christian Brauner: "Last cycle we introduce f_op->mmap_prepare() in c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file callback"). This is preferred to the existing f_op->mmap() hook as it does require a VMA to be established yet, thus allowing the mmap logic to invoke this hook far, far earlier, prior to inserting a VMA into the virtual address space, or performing any other heavy handed operations. This allows for much simpler unwinding on error, and for there to be a single attempt at merging a VMA rather than having to possibly reattempt a merge based on potentially altered VMA state. Far more importantly, it prevents inappropriate manipulation of incompletely initialised VMA state, which is something that has been the cause of bugs and complexity in the past. The intent is to gradually deprecate f_op->mmap, and in that vein this series coverts the majority of file systems to using f_op->mmap_prepare. Prerequisite steps are taken - firstly ensuring all checks for mmap capabilities use the file_has_valid_mmap_hooks() helper rather than directly checking for f_op->mmap (which is now not a valid check) and secondly updating daxdev_mapping_supported() to not require a VMA parameter to allow ext4 and xfs to be converted. Commit bb666b7c2707 ("mm: add mmap_prepare() compatibility layer for nested file systems") handles the nasty edge-case of nested file systems like overlayfs, which introduces a compatibility shim to allow f_op->mmap_prepare() to be invoked from an f_op->mmap() callback. This allows for nested filesystems to continue to function correctly with all file systems regardless of which callback is used. Once we finally convert all file systems, this shim can be removed. As a result, ecryptfs, fuse, and overlayfs remain unaltered so they can nest all other file systems. We additionally do not update resctl - as this requires an update to remap_pfn_range() (or an alternative to it) which we defer to a later series, equally we do not update cramfs which needs a mixed mapping insertion with the same issue, nor do we update procfs, hugetlbfs, syfs or kernfs all of which require VMAs for internal state and hooks. We shall return to all of these later" * tag 'vfs-6.17-rc1.mmap_prepare' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: doc: update porting, vfs documentation to describe mmap_prepare() fs: replace mmap hook with .mmap_prepare for simple mappings fs: convert most other generic_file_*mmap() users to .mmap_prepare() fs: convert simple use of generic_file_*_mmap() to .mmap_prepare() mm/filemap: introduce generic_file_*_mmap_prepare() helpers fs/xfs: transition from deprecated .mmap hook to .mmap_prepare fs/ext4: transition from deprecated .mmap hook to .mmap_prepare fs/dax: make it possible to check dev dax support without a VMA fs: consistently use can_mmap_file() helper mm/nommu: use file_has_valid_mmap_hooks() helper mm: rename call_mmap/mmap_prepare to vfs_mmap/mmap_prepare

fs: change write_begin/write_end interface to take struct kiocb *

2025-07-16T12:48:18+00:00

Change the address_space_operations callbacks write_begin() and write_end() to take struct kiocb * as the first argument instead of struct file *. Update all affected function prototypes, implementations, call sites, and related documentation across VFS, filesystems, and block layer. Part of a series refactoring address_space_operations write_begin and write_end callbacks to use struct kiocb for passing write context and flags. Signed-off-by: Taotao Chen Link: https://lore.kernel.org/20250716093559.217344-4-chentaotao@didiglobal.com Signed-off-by: Christian Brauner

fs: replace mmap hook with .mmap_prepare for simple mappings

2025-06-19T11:56:59+00:00

Since commit c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file callback"), the f_op->mmap() hook has been deprecated in favour of f_op->mmap_prepare(). This callback is invoked in the mmap() logic far earlier, so error handling can be performed more safely without complicated and bug-prone state unwinding required should an error arise. This hook also avoids passing a pointer to a not-yet-correctly-established VMA avoiding any issues with referencing this data structure. It rather provides a pointer to the new struct vm_area_desc descriptor type which contains all required state and allows easy setting of required parameters without any consideration needing to be paid to locking or reference counts. Note that nested filesystems like overlayfs are compatible with an .mmap_prepare() callback since commit bb666b7c2707 ("mm: add mmap_prepare() compatibility layer for nested file systems"). In this patch we apply this change to file systems with relatively simple mmap() hook logic - exfat, ceph, f2fs, bcachefs, zonefs, btrfs, ocfs2, orangefs, nilfs2, romfs, ramfs and aio. Signed-off-by: Lorenzo Stoakes Link: https://lore.kernel.org/f528ac4f35b9378931bd800920fee53fc0c5c74d.1750099179.git.lorenzo.stoakes@oracle.com Acked-by: Damien Le Moal Reviewed-by: Jan Kara Reviewed-by: Viacheslav Dubeyko Signed-off-by: Christian Brauner