kernel/linux.git/fs/netfs/misc.c, branch v6.12.80

netfs: Fix a KMSAN uninit-value error in netfs_clear_buffer

2024-10-01T14:02:42+00:00

Use folioq_count instead of folioq_nr_slots to fix a KMSAN uninit-value error in netfs_clear_buffer Signed-off-by: Chang Yu Link: https://lore.kernel.org/r/ZvuXWC2bYpvQsWgS@gmail.com Fixes: cd0277ed0c18 ("netfs: Use new folio_queue data type and iterator instead of xarray iter") Acked-by: David Howells Reported-by: syzbot+921873345a95f4dae7e9@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=921873345a95f4dae7e9 Signed-off-by: Christian Brauner

netfs: Fix write oops in generic/346 (9p) and generic/074 (cifs)

2024-09-26T22:45:20+00:00

In netfslib, a buffered writeback operation has a 'write queue' of folios that are being written, held in a linear sequence of folio_queue structs. The 'issuer' adds new folio_queues on the leading edge of the queue and populates each one progressively; the 'collector' pops them off the trailing edge and discards them and the folios they point to as they are consumed. The queue is required to always retain at least one folio_queue structure. This allows the queue to be accessed without locking and with just a bit of barriering. When a new subrequest is prepared, its ->io_iter iterator is pointed at the current end of the write queue and then the iterator is extended as more data is added to the queue until the subrequest is committed. Now, the problem is that the folio_queue at the leading edge of the write queue when a subrequest is prepared might have been entirely consumed - but not yet removed from the queue as it is the only remaining one and is preventing the queue from collapsing. So, what happens is that subreq->io_iter is pointed at the spent folio_queue, then a new folio_queue is added, and, at that point, the collector is at entirely at liberty to immediately delete the spent folio_queue. This leaves the subreq->io_iter pointing at a freed object. If the system is lucky, iterate_folioq() sees ->io_iter, sees the as-yet uncorrupted freed object and advances to the next folio_queue in the queue. In the case seen, however, the freed object gets recycled and put back onto the queue at the tail and filled to the end. This confuses iterate_folioq() and it tries to step ->next, which may be NULL - resulting in an oops. Fix this by the following means: (1) When preparing a write subrequest, make sure there's a folio_queue struct with space in it at the leading edge of the queue. A function to make space is split out of the function to append a folio so that it can be called for this purpose. (2) If the request struct iterator is pointing to a completely spent folio_queue when we make space, then advance the iterator to the newly allocated folio_queue. The subrequest's iterator will then be set from this. The oops could be triggered using the generic/346 xfstest with a filesystem on9P over TCP with cache=loose. The oops looked something like: BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page ... RIP: 0010:_copy_from_iter+0x2db/0x530 ... Call Trace: ... p9pdu_vwritef+0x3d8/0x5d0 p9_client_prepare_req+0xa8/0x140 p9_client_rpc+0x81/0x280 p9_client_write+0xcf/0x1c0 v9fs_issue_write+0x87/0xc0 netfs_advance_write+0xa0/0xb0 netfs_write_folio.isra.0+0x42d/0x500 netfs_writepages+0x15a/0x1f0 do_writepages+0xd1/0x220 filemap_fdatawrite_wbc+0x5c/0x80 v9fs_mmap_vm_close+0x7d/0xb0 remove_vma+0x35/0x70 vms_complete_munmap_vmas+0x11a/0x170 do_vmi_align_munmap+0x17d/0x1c0 do_vmi_munmap+0x13e/0x150 __vm_munmap+0x92/0xd0 __x64_sys_munmap+0x17/0x20 do_syscall_64+0x80/0xe0 entry_SYSCALL_64_after_hwframe+0x71/0x79 This also fixed a similar-looking issue with cifs and generic/074. Fixes: cd0277ed0c18 ("netfs: Use new folio_queue data type and iterator instead of xarray iter") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202409180928.f20b5a08-oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202409131438.3f225fbf-oliver.sang@intel.com Signed-off-by: David Howells Tested-by: kernel test robot cc: Eric Van Hensbergen cc: Latchesar Ionkov cc: Dominique Martinet cc: Christian Schoenebeck cc: Paulo Alcantara cc: Jeff Layton cc: v9fs@lists.linux.dev cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Steve French

netfs: Provide an iterator-reset function

2024-09-12T10:20:40+00:00

Provide a function to reset the iterator on a subrequest. 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/20240814203850.2240469-17-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner

netfs: Use new folio_queue data type and iterator instead of xarray iter

2024-09-12T10:20:40+00:00

Make the netfs write-side routines use the new folio_queue struct to hold a rolling buffer of folios, with the issuer adding folios at the tail and the collector removing them from the head as they're processed instead of using an xarray. This will allow a subsequent patch to simplify the write collector. The primary mark (as tested by folioq_is_marked()) is used to note if the corresponding folio needs putting. 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/20240814203850.2240469-16-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner

netfs: Fix trimming of streaming-write folios in netfs_inval_folio()

2024-08-24T14:09:16+00:00

When netfslib writes to a folio that it doesn't have data for, but that data exists on the server, it will make a 'streaming write' whereby it stores data in a folio that is marked dirty, but not uptodate. When it does this, it attaches a record to folio->private to track the dirty region. When truncate() or fallocate() wants to invalidate part of such a folio, it will call into ->invalidate_folio(), specifying the part of the folio that is to be invalidated. netfs_invalidate_folio(), on behalf of the filesystem, must then determine how to trim the streaming write record. In a couple of cases, however, it does this incorrectly (the reduce-length and move-start cases are switched over and don't, in any case, calculate the value correctly). Fix this by making the logic tree more obvious and fixing the cases. Fixes: 9ebff83e6481 ("netfs: Prep to use folio->private for write grouping and streaming write") Signed-off-by: David Howells Link: https://lore.kernel.org/r/20240823200819.532106-5-dhowells@redhat.com cc: Matthew Wilcox (Oracle) cc: Pankaj Raghav cc: Jeff Layton cc: Marc Dionne cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-mm@kvack.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs: Fix netfs_release_folio() to say no if folio dirty

2024-08-24T14:09:16+00:00

Fix netfs_release_folio() to say no (ie. return false) if the folio is dirty (analogous with iomap's behaviour). Without this, it will say yes to the release of a dirty page by split_huge_page_to_list_to_order(), which will result in the loss of untruncated data in the folio. Without this, the generic/075 and generic/112 xfstests (both fsx-based tests) fail with minimum folio size patches applied[1]. Fixes: c1ec4d7c2e13 ("netfs: Provide invalidate_folio and release_folio calls") Signed-off-by: David Howells Link: https://lore.kernel.org/r/20240815090849.972355-1-kernel@pankajraghav.com/ [1] Link: https://lore.kernel.org/r/20240823200819.532106-4-dhowells@redhat.com cc: Matthew Wilcox (Oracle) cc: Pankaj Raghav cc: Jeff Layton cc: Marc Dionne cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-mm@kvack.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs, ceph: Partially revert "netfs: Replace PG_fscache by setting folio->private and marking dirty"

2024-08-21T20:32:58+00:00

This partially reverts commit 2ff1e97587f4d398686f52c07afde3faf3da4e5c. In addition to reverting the removal of PG_private_2 wrangling from the buffered read code[1][2], the removal of the waits for PG_private_2 from netfs_release_folio() and netfs_invalidate_folio() need reverting too. It also adds a wait into ceph_evict_inode() to wait for netfs read and copy-to-cache ops to complete. Fixes: 2ff1e97587f4 ("netfs: Replace PG_fscache by setting folio->private and marking dirty") Signed-off-by: David Howells Link: https://lore.kernel.org/r/3575457.1722355300@warthog.procyon.org.uk [1] Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8e5ced7804cb9184c4a23f8054551240562a8eda [2] Link: https://lore.kernel.org/r/20240814203850.2240469-2-dhowells@redhat.com cc: Max Kellermann cc: Ilya Dryomov cc: Xiubo Li cc: Jeff Layton cc: Matthew Wilcox cc: ceph-devel@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org 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

Merge tag 'vfs-6.10-rc8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-07-11T16:03:28+00:00

Pull vfs fixes from Christian Brauner: "cachefiles: - Export an existing and add a new cachefile helper to be used in filesystems to fix reference count bugs - Use the newly added fscache_ty_get_volume() helper to get a reference count on an fscache_volume to handle volumes that are about to be removed cleanly - After withdrawing a fscache_cache via FSCACHE_CACHE_IS_WITHDRAWN wait for all ongoing cookie lookups to complete and for the object count to reach zero - Propagate errors from vfs_getxattr() to avoid an infinite loop in cachefiles_check_volume_xattr() because it keeps seeing ESTALE - Don't send new requests when an object is dropped by raising CACHEFILES_ONDEMAND_OJBSTATE_DROPPING - Cancel all requests for an object that is about to be dropped - Wait for the ondemand_boject_worker to finish before dropping a cachefiles object to prevent use-after-free - Use cyclic allocation for message ids to better handle id recycling - Add missing lock protection when iterating through the xarray when polling netfs: - Use standard logging helpers for debug logging VFS: - Fix potential use-after-free in file locks during trace_posix_lock_inode(). The tracepoint could fire while another task raced it and freed the lock that was requested to be traced - Only increment the nr_dentry_negative counter for dentries that are present on the superblock LRU. Currently, DCACHE_LRU_LIST list is used to detect this case. However, the flag is also raised in combination with DCACHE_SHRINK_LIST to indicate that dentry->d_lru is used. So checking only DCACHE_LRU_LIST will lead to wrong nr_dentry_negative count. Fix the check to not count dentries that are on a shrink related list Misc: - hfsplus: fix an uninitialized value issue in copy_name - minix: fix minixfs_rename with HIGHMEM. It still uses kunmap() even though we switched it to kmap_local_page() a while ago" * tag 'vfs-6.10-rc8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: minixfs: Fix minixfs_rename with HIGHMEM hfsplus: fix uninit-value in copy_name vfs: don't mod negative dentry count when on shrinker list filelock: fix potential use-after-free in posix_lock_inode cachefiles: add missing lock protection when polling cachefiles: cyclic allocation of msg_id to avoid reuse cachefiles: wait for ondemand_object_worker to finish when dropping object cachefiles: cancel all requests for the object that is being dropped cachefiles: stop sending new request when dropping object cachefiles: propagate errors from vfs_getxattr() to avoid infinite loop cachefiles: fix slab-use-after-free in cachefiles_withdraw_cookie() cachefiles: fix slab-use-after-free in fscache_withdraw_volume() netfs, fscache: export fscache_put_volume() and add fscache_try_get_volume() netfs: Switch debug logging to pr_debug()

netfs: Delete some xarray-wangling functions that aren't used

2024-06-26T12:16:49+00:00

Delete some xarray-based buffer wangling functions that are intended for use with bounce buffering, but aren't used because bounce-buffering got deferred to a later patch series. Now, however, the intention is to use something other than an xarray to do this. 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/20240620173137.610345-9-dhowells@redhat.com Signed-off-by: Christian Brauner