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| author | David Howells <dhowells@redhat.com> | 2024-01-29 12:49:19 +0300 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-01-29 16:53:21 +0300 |
| commit | ca9ca1a5d5a980550db1001ea825f9fdfa550b83 (patch) | |
| tree | 8581ba3b07f5f16066883d3d566bc35c5e314120 /fs/netfs | |
| parent | 2147caaac7349698f2a392c5e2911a6861a09650 (diff) | |
| download | linux-ca9ca1a5d5a980550db1001ea825f9fdfa550b83.tar.xz | |
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: 153a9961b551 ("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>
Diffstat (limited to 'fs/netfs')
| -rw-r--r-- | fs/netfs/buffered_write.c | 3 | ||||
| -rw-r--r-- | fs/netfs/direct_write.c | 5 |
2 files changed, 7 insertions, 1 deletions
diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c index a3059b3168fd..9a0d32e4b422 100644 --- a/fs/netfs/buffered_write.c +++ b/fs/netfs/buffered_write.c @@ -477,6 +477,9 @@ ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from) _enter("%llx,%zx,%llx", iocb->ki_pos, iov_iter_count(from), i_size_read(inode)); + if (!iov_iter_count(from)) + return 0; + if ((iocb->ki_flags & IOCB_DIRECT) || test_bit(NETFS_ICTX_UNBUFFERED, &ictx->flags)) return netfs_unbuffered_write_iter(iocb, from); diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c index 60a40d293c87..bee047e20f5d 100644 --- a/fs/netfs/direct_write.c +++ b/fs/netfs/direct_write.c @@ -139,6 +139,9 @@ ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from) _enter("%llx,%zx,%llx", iocb->ki_pos, iov_iter_count(from), i_size_read(inode)); + if (!iov_iter_count(from)) + return 0; + trace_netfs_write_iter(iocb, from); netfs_stat(&netfs_n_rh_dio_write); @@ -146,7 +149,7 @@ ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from) if (ret < 0) return ret; ret = generic_write_checks(iocb, from); - if (ret < 0) + if (ret <= 0) goto out; ret = file_remove_privs(file); if (ret < 0) |