summaryrefslogtreecommitdiff
path: root/fs/netfs
diff options
context:
space:
mode:
authorDavid Howells <dhowells@redhat.com>2024-01-29 12:49:19 +0300
committerChristian Brauner <brauner@kernel.org>2024-01-29 16:53:21 +0300
commitca9ca1a5d5a980550db1001ea825f9fdfa550b83 (patch)
tree8581ba3b07f5f16066883d3d566bc35c5e314120 /fs/netfs
parent2147caaac7349698f2a392c5e2911a6861a09650 (diff)
downloadlinux-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.c3
-rw-r--r--fs/netfs/direct_write.c5
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)