linux/fs/netfs
David Howells ca9ca1a5d5 netfs: Fix missing zero-length check in unbuffered write
Fix netfs_unbuffered_write_iter() to return immediately if
generic_write_checks() returns 0, indicating there's nothing to write.
Note that netfs_file_write_iter() already does this.

Also, whilst we're at it, put in checks for the size being zero before we
even take the locks.  Note that generic_write_checks() can still reduce the
size to zero, so we still need that check.

Without this, a warning similar to the following is logged to dmesg:

	netfs: Zero-sized write [R=1b6da]

and the syscall fails with EIO, e.g.:

	/sbin/ldconfig.real: Writing of cache extension data failed: Input/output error

This can be reproduced on 9p by:

	xfs_io -f -c 'pwrite 0 0' /xfstest.test/foo

Fixes: 153a9961b5 ("netfs: Implement unbuffered/DIO write support")
Reported-by: Eric Van Hensbergen <ericvh@kernel.org>
Link: https://lore.kernel.org/r/ZbQUU6QKmIftKsmo@FV7GG9FTHL/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20240129094924.1221977-3-dhowells@redhat.com
Tested-by: Dominique Martinet <asmadeus@codewreck.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Dominique Martinet <asmadeus@codewreck.org>
cc: Jeff Layton <jlayton@kernel.org>
cc:  <v9fs@lists.linux.dev>
cc:  <linux_oss@crudebyte.com>
cc:  <netfs@lists.linux.dev>
cc:  <linux-fsdevel@vger.kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-01-29 14:53:21 +01:00
..
buffered_read.c netfs: Don't use certain unnecessary folio_*() functions 2024-01-22 21:56:11 +00:00
buffered_write.c netfs: Fix missing zero-length check in unbuffered write 2024-01-29 14:53:21 +01:00
direct_read.c netfs: Implement unbuffered/DIO read support 2023-12-28 09:45:23 +00:00
direct_write.c netfs: Fix missing zero-length check in unbuffered write 2024-01-29 14:53:21 +01:00
fscache_cache.c netfs, fscache: Prevent Oops in fscache_put_cache() 2024-01-22 21:58:35 +00:00
fscache_cookie.c netfs, fscache: Move fs/fscache/* into fs/netfs/ 2023-12-24 11:36:00 +00:00
fscache_internal.h netfs, fscache: Combine fscache with netfs 2023-12-24 15:08:46 +00:00
fscache_io.c netfs, cachefiles: Pass upper bound length to allow expansion 2023-12-28 09:45:25 +00:00
fscache_main.c netfs, fscache: Move /proc/fs/fscache to /proc/fs/netfs and put in a symlink 2023-12-24 15:08:48 +00:00
fscache_proc.c netfs: Fix proc/fs/fscache symlink to point to "netfs" not "../netfs" 2024-01-04 13:15:32 +00:00
fscache_stats.c netfs: Fix interaction between write-streaming and cachefiles culling 2024-01-05 15:42:25 +00:00
fscache_volume.c netfs, fscache: Move fs/fscache/* into fs/netfs/ 2023-12-24 11:36:00 +00:00
internal.h netfs: Fix interaction between write-streaming and cachefiles culling 2024-01-05 15:42:25 +00:00
io.c netfs: Fix i_dio_count leak on DIO read past i_size 2024-01-29 14:53:18 +01:00
iterator.c netfs: Add func to calculate pagecount/size-limited span of an iterator 2023-12-28 09:45:18 +00:00
Kconfig netfs, fscache: Combine fscache with netfs 2023-12-24 15:08:46 +00:00
locking.c netfs: Implement unbuffered/DIO vs buffered I/O locking 2023-12-24 15:08:52 +00:00
main.c netfs: Export the netfs_sreq tracepoint 2023-12-28 09:45:27 +00:00
Makefile netfs: Implement unbuffered/DIO write support 2023-12-28 09:45:24 +00:00
misc.c netfs: Don't use certain unnecessary folio_*() functions 2024-01-22 21:56:11 +00:00
objects.c netfs: Implement a write-through caching option 2023-12-28 09:45:27 +00:00
output.c netfs: Implement a write-through caching option 2023-12-28 09:45:27 +00:00
stats.c netfs: Fix interaction between write-streaming and cachefiles culling 2024-01-05 15:42:25 +00:00