kernel/linux.git/fs/netfs/iterator.c, branch v7.1-rc5

netfs: Fix overrun check in netfs_extract_user_iter()

2026-05-12T12:42:30+00:00

Fix netfs_extract_user_iter() so that if iov_iter_extract_pages() overfills pages[], then those pages don't get included in the iterator constructed at the end of the function. If there was an overfill, memory corruption has already happened. Fixes: 85dd2c8ff368 ("netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator") Closes: https://sashiko.dev/#/patchset/20260427154639.180684-1-dhowells%40redhat.com Signed-off-by: David Howells Link: https://patch.msgid.link/20260512123404.719402-11-dhowells@redhat.com cc: Paulo Alcantara cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs: fix error handling in netfs_extract_user_iter()

2026-05-12T12:42:30+00:00

In netfs_extract_user_iter(), if iov_iter_extract_pages() failed to extract user pages, bail out on -ENOMEM, otherwise return the error code only if @npages == 0, allowing short DIO reads and writes to be issued. This fixes mmapstress02 from LTP tests against CIFS. Fixes: 85dd2c8ff368 ("netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator") Reported-by: Xiaoli Feng Signed-off-by: Paulo Alcantara (Red Hat) Signed-off-by: David Howells Link: https://patch.msgid.link/20260512123404.719402-10-dhowells@redhat.com Cc: netfs@lists.linux.dev Cc: stable@vger.kernel.org Cc: linux-cifs@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs: Fix potential uninitialised var in netfs_extract_user_iter()

2026-05-12T12:42:30+00:00

In netfs_extract_user_iter(), if it's given a zero-length iterator, it will fall through the loop without setting ret, and so the error handling behaviour will be undefined, depending on whether ret happens to be negative. The value of ret then propagates back up the callstack. Fix this by presetting ret to 0. Fixes: 85dd2c8ff368 ("netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator") Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com Signed-off-by: David Howells Link: https://patch.msgid.link/20260512123404.719402-9-dhowells@redhat.com cc: Paulo Alcantara cc: Matthew Wilcox cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner

netfs: Fix kernel BUG in netfs_limit_iter() for ITER_KVEC iterators

2026-03-09T09:17:00+00:00

When a process crashes and the kernel writes a core dump to a 9P filesystem, __kernel_write() creates an ITER_KVEC iterator. This iterator reaches netfs_limit_iter() via netfs_unbuffered_write(), which only handles ITER_FOLIOQ, ITER_BVEC and ITER_XARRAY iterator types, hitting the BUG() for any other type. Fix this by adding netfs_limit_kvec() following the same pattern as netfs_limit_bvec(), since both kvec and bvec are simple segment arrays with pointer and length fields. Dispatch it from netfs_limit_iter() when the iterator type is ITER_KVEC. Fixes: cae932d3aee5 ("netfs: Add func to calculate pagecount/size-limited span of an iterator") Reported-by: syzbot+9c058f0d63475adc97fd@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9c058f0d63475adc97fd Tested-by: syzbot+9c058f0d63475adc97fd@syzkaller.appspotmail.com Signed-off-by: Deepanshu Kartikey Link: https://patch.msgid.link/20260307090041.359870-1-kartikey406@gmail.com Signed-off-by: Christian Brauner

netfs: Speed up buffered reading

2024-09-12T10:20:41+00:00

Improve the efficiency of buffered reads in a number of ways: (1) Overhaul the algorithm in general so that it's a lot more compact and split the read submission code between buffered and unbuffered versions. The unbuffered version can be vastly simplified. (2) Read-result collection is handed off to a work queue rather than being done in the I/O thread. Multiple subrequests can be processes simultaneously. (3) When a subrequest is collected, any folios it fully spans are collected and "spare" data on either side is donated to either the previous or the next subrequest in the sequence. Notes: (*) Readahead expansion is massively slows down fio, presumably because it causes a load of extra allocations, both folio and xarray, up front before RPC requests can be transmitted. (*) RDMA with cifs does appear to work, both with SIW and RXE. (*) PG_private_2-based reading and copy-to-cache is split out into its own file and altered to use folio_queue. Note that the copy to the cache now creates a new write transaction against the cache and adds the folios to be copied into it. This allows it to use part of the writeback I/O code. 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/20240814203850.2240469-20-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner

netfs: Add func to calculate pagecount/size-limited span of an iterator

2023-12-28T09:45:18+00:00

Add a function to work out how much of an ITER_BVEC or ITER_XARRAY iterator we can use in a pagecount-limited and size-limited span. This will be used, for example, to limit the number of segments in a subrequest to the maximum number of elements that an RDMA transfer can handle. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org

Move netfs_extract_iter_to_sg() to lib/scatterlist.c

2023-06-08T11:42:33+00:00

Move netfs_extract_iter_to_sg() to lib/scatterlist.c as it's going to be used by more than just network filesystems (AF_ALG, for example). Signed-off-by: David Howells cc: Jeff Layton cc: Steve French cc: Shyam Prasad N cc: Rohith Surabattula cc: Jens Axboe cc: Herbert Xu cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Matthew Wilcox cc: linux-crypto@vger.kernel.org cc: linux-cachefs@redhat.com cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: netdev@vger.kernel.org Signed-off-by: Paolo Abeni

Wrap lines at 80

2023-06-08T11:42:33+00:00

Wrap a line at 80 to stop checkpatch complaining. Signed-off-by: David Howells cc: Jeff Layton cc: Steve French cc: Shyam Prasad N cc: Rohith Surabattula cc: Jens Axboe cc: Herbert Xu cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Matthew Wilcox cc: Simon Horman cc: linux-crypto@vger.kernel.org cc: linux-cachefs@redhat.com cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: netdev@vger.kernel.org Signed-off-by: Paolo Abeni

Fix a couple of spelling mistakes

2023-06-08T11:42:33+00:00

Fix a couple of spelling mistakes in a comment. Suggested-by: Simon Horman Link: https://lore.kernel.org/r/ZHH2mSRqeL4Gs1ft@corigine.com/ Link: https://lore.kernel.org/r/ZHH1nqZWOGzxlidT@corigine.com/ Signed-off-by: David Howells Reviewed-by: Simon Horman cc: Jeff Layton cc: Steve French cc: Shyam Prasad N cc: Rohith Surabattula cc: Jens Axboe cc: Herbert Xu cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Matthew Wilcox cc: linux-crypto@vger.kernel.org cc: linux-cachefs@redhat.com cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: netdev@vger.kernel.org Signed-off-by: Paolo Abeni

Drop the netfs_ prefix from netfs_extract_iter_to_sg()

2023-06-08T11:42:33+00:00

Rename netfs_extract_iter_to_sg() and its auxiliary functions to drop the netfs_ prefix. Signed-off-by: David Howells cc: Jeff Layton cc: Steve French cc: Shyam Prasad N cc: Rohith Surabattula cc: Jens Axboe cc: Herbert Xu cc: "Matthew Wilcox (Oracle)" cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: linux-crypto@vger.kernel.org cc: linux-cachefs@redhat.com cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: netdev@vger.kernel.org Signed-off-by: Paolo Abeni