kernel.git/fs/netfs/misc.c, branch linux-6.15.y

netfs: Fix double put of request

2025-07-10T14:08:46Z

[ Upstream commit 9df7b5ebead649b00bf9a53a798e4bf83a1318fd ] If a netfs request finishes during the pause loop, it will have the ref that belongs to the IN_PROGRESS flag removed at that point - however, if it then goes to the final wait loop, that will *also* put the ref because it sees that the IN_PROGRESS flag is clear and incorrectly assumes that this happened when it called the collector. In fact, since IN_PROGRESS is clear, we shouldn't call the collector again since it's done all the cleanup, such as calling ->ki_complete(). Fix this by making netfs_collect_in_app() just return, indicating that we're done if IN_PROGRESS is removed. Fixes: 2b1424cd131c ("netfs: Fix wait/wake to be consistent about the waitqueue used") Signed-off-by: David Howells Link: https://lore.kernel.org/20250701163852.2171681-3-dhowells@redhat.com Tested-by: Steve French Reviewed-by: Paulo Alcantara cc: Steve French cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org cc: linux-cifs@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Fix looping in wait functions

2025-07-10T14:08:43Z

[ Upstream commit 09623e3a14c1c5465124350cd227457c2b0fb017 ] netfs_wait_for_request() and netfs_wait_for_pause() can loop forever if netfs_collect_in_app() returns 2, indicating that it wants to repeat because the ALL_QUEUED flag isn't yet set and there are no subreqs left that haven't been collected. The problem is that, unless collection is offloaded (OFFLOAD_COLLECTION), we have to return to the application thread to continue and eventually set ALL_QUEUED after pausing to deal with a retry - but we never get there. Fix this by inserting checks for the IN_PROGRESS and PAUSE flags as appropriate before cycling round - and add cond_resched() for good measure. Fixes: 2b1424cd131c ("netfs: Fix wait/wake to be consistent about the waitqueue used") Signed-off-by: David Howells Link: https://lore.kernel.org/20250701163852.2171681-5-dhowells@redhat.com Tested-by: Steve French Reviewed-by: Paulo Alcantara cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Fix hang due to missing case in final DIO read result collection

2025-07-10T14:08:43Z

[ Upstream commit da8cf4bd458722d090a788c6e581eeb72695c62f ] When doing a DIO read, if the subrequests we issue fail and cause the request PAUSE flag to be set to put a pause on subrequest generation, we may complete collection of the subrequests (possibly discarding them) prior to the ALL_QUEUED flags being set. In such a case, netfs_read_collection() doesn't see ALL_QUEUED being set after netfs_collect_read_results() returns and will just return to the app (the collector can be seen unpausing the generator in the trace log). The subrequest generator can then set ALL_QUEUED and the app thread reaches netfs_wait_for_request(). This causes netfs_collect_in_app() to be called to see if we're done yet, but there's missing case here. netfs_collect_in_app() will see that a thread is active and set inactive to false, but won't see any subrequests in the read stream, and so won't set need_collect to true. The function will then just return 0, indicating that the caller should just sleep until further activity (which won't be forthcoming) occurs. Fix this by making netfs_collect_in_app() check to see if an active thread is complete - i.e. that ALL_QUEUED is set and the subrequests list is empty - and to skip the sleep return path. The collector will then be called which will clear the request IN_PROGRESS flag, allowing the app to progress. Fixes: 2b1424cd131c ("netfs: Fix wait/wake to be consistent about the waitqueue used") Reported-by: Steve French Signed-off-by: David Howells Link: https://lore.kernel.org/20250701163852.2171681-2-dhowells@redhat.com Tested-by: Steve French Reviewed-by: Paulo Alcantara cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Fix undifferentiation of DIO reads from unbuffered reads

2025-06-19T13:40:21Z

[ Upstream commit db26d62d79e4068934ad0dccdb92715df36352b9 ] On cifs, "DIO reads" (specified by O_DIRECT) need to be differentiated from "unbuffered reads" (specified by cache=none in the mount parameters). The difference is flagged in the protocol and the server may behave differently: Windows Server will, for example, mandate that DIO reads are block aligned. Fix this by adding a NETFS_UNBUFFERED_READ to differentiate this from NETFS_DIO_READ, parallelling the write differentiation that already exists. cifs will then do the right thing. Fixes: 016dc8516aec ("netfs: Implement unbuffered/DIO read support") Signed-off-by: David Howells Link: https://lore.kernel.org/3444961.1747987072@warthog.procyon.org.uk Reviewed-by: "Paulo Alcantara (Red Hat)" Reviewed-by: Viacheslav Dubeyko cc: Steve French cc: netfs@lists.linux.dev cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: linux-cifs@vger.kernel.org cc: ceph-devel@vger.kernel.org cc: linux-nfs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

netfs: Fix wait/wake to be consistent about the waitqueue used

2025-06-19T13:40:21Z

[ Upstream commit 2b1424cd131cfaba4cf7040473133d26cddac088 ] Fix further inconsistencies in the use of waitqueues (clear_and_wake_up_bit() vs private waitqueue). Move some of this stuff from the read and write sides into common code so that it can be done in fewer places. To make this work, async I/O needs to set NETFS_RREQ_OFFLOAD_COLLECTION to indicate that a workqueue will do the collecting and places that call the wait function need to deal with it returning the amount transferred. Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item") Signed-off-by: David Howells Link: https://lore.kernel.org/20250519090707.2848510-5-dhowells@redhat.com cc: Marc Dionne cc: Steve French cc: Ihor Solodrai 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: Christian Brauner Signed-off-by: Sasha Levin

netfs: Add functions to build/clean a buffer in a folio_queue

2024-12-20T21:34:06Z

Add two netfslib functions to build up or clean up a buffer in a folio_queue. The first, netfs_alloc_folioq_buffer() will add folios to a buffer, extending up at least to the given size. If it can, it will add multipage folios. The folios are optionally have the mapping set and will have the index set according to the distance from the front of the folio queue. The second function will free up a folio queue and put any folios in the queue that have the first mark set. The netfs_folio tracepoint is also altered to cope with folios that have a NULL mapping, and the folios being added/put will have trace lines emitted and will be accounted in the stats. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20241216204124.3752367-19-dhowells@redhat.com cc: Jeff Layton cc: Marc Dionne cc: netfs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs: Abstract out a rolling folio buffer implementation

2024-12-20T21:34:02Z

A rolling buffer is a series of folios held in a list of folio_queues. New folios and folio_queue structs may be inserted at the head simultaneously with spent ones being removed from the tail without the need for locking. The rolling buffer includes an iov_iter and it has to be careful managing this as the list of folio_queues is extended such that an oops doesn't incurred because the iterator was pointing to the end of a folio_queue segment that got appended to and then removed. We need to use the mechanism twice, once for read and once for write, and, in future patches, we will use a second rolling buffer to handle bounce buffering for content encryption. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20241216204124.3752367-6-dhowells@redhat.com cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs: Add a tracepoint to log the lifespan of folio_queue structs

2024-12-20T21:34:02Z

Add a tracepoint to log the lifespan of folio_queue structs. For tracing illustrative purposes, folio_queues are tagged with the debug ID of whatever they're related to (typically a netfs_io_request) and a debug ID of their own. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20241216204124.3752367-5-dhowells@redhat.com cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs: Use a folio_queue allocation and free functions

2024-12-20T21:34:02Z

Provide and use folio_queue allocation and free functions to combine the allocation, initialisation and stat (un)accounting steps that are repeated in several places. Signed-off-by: David Howells Link: https://lore.kernel.org/r/20241216204124.3752367-4-dhowells@redhat.com cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs: Fix a KMSAN uninit-value error in netfs_clear_buffer

2024-10-01T14:02:42Z

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