From: David Howells <dhowells@redhat.com> To: Christian Brauner <christian@brauner.io> Cc: David Howells <dhowells@redhat.com>, Eric Van Hensbergen <ericvh@kernel.org>, Dominique Martinet <asmadeus@codewreck.org>, Jeff Layton <jlayton@kernel.org>, Matthew Wilcox <willy@infradead.org>, netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux_oss@crudebyte.com Subject: [PATCH 2/2] netfs: Fix missing zero-length check in unbuffered write Date: Mon, 29 Jan 2024 09:49:19 +0000 [thread overview] Message-ID: <20240129094924.1221977-3-dhowells@redhat.com> (raw) In-Reply-To: <20240129094924.1221977-1-dhowells@redhat.com> 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> 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 --- fs/netfs/buffered_write.c | 3 +++ fs/netfs/direct_write.c | 5 ++++- 2 files changed, 7 insertions(+), 1 deletion(-) 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)
WARNING: multiple messages have this Message-ID (diff)
From: David Howells <dhowells@redhat.com> To: Christian Brauner <christian@brauner.io> Cc: linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, v9fs@lists.linux.dev, Dominique Martinet <asmadeus@codewreck.org>, linux_oss@crudebyte.com, Jeff Layton <jlayton@kernel.org>, linux-kernel@vger.kernel.org, Matthew Wilcox <willy@infradead.org>, David Howells <dhowells@redhat.com>, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, netfs@lists.linux.dev, ceph-devel@vger.kernel.org, Eric Van Hensbergen <ericvh@kernel.org>, linux-erofs@lists.ozlabs.org, linux-afs@lists.infradead.org Subject: [PATCH 2/2] netfs: Fix missing zero-length check in unbuffered write Date: Mon, 29 Jan 2024 09:49:19 +0000 [thread overview] Message-ID: <20240129094924.1221977-3-dhowells@redhat.com> (raw) In-Reply-To: <20240129094924.1221977-1-dhowells@redhat.com> 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> 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 --- fs/netfs/buffered_write.c | 3 +++ fs/netfs/direct_write.c | 5 ++++- 2 files changed, 7 insertions(+), 1 deletion(-) 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)
next prev parent reply other threads:[~2024-01-29 9:49 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-01-29 9:49 [PATCH 0/2] netfs: Miscellaneous fixes David Howells 2024-01-29 9:49 ` David Howells 2024-01-29 9:49 ` [PATCH 1/2] netfs: Fix i_dio_count leak on DIO read past i_size David Howells 2024-01-29 9:49 ` David Howells 2024-01-29 12:41 ` Jeff Layton 2024-01-29 12:41 ` Jeff Layton 2024-01-29 9:49 ` David Howells [this message] 2024-01-29 9:49 ` [PATCH 2/2] netfs: Fix missing zero-length check in unbuffered write David Howells 2024-01-29 12:43 ` Jeff Layton 2024-01-29 12:43 ` Jeff Layton 2024-01-30 21:57 ` Dominique Martinet 2024-01-30 21:57 ` Dominique Martinet 2024-02-19 8:38 ` Linux regression tracking (Thorsten Leemhuis) 2024-02-19 8:38 ` Linux regression tracking (Thorsten Leemhuis) 2024-02-20 9:51 ` Christian Brauner 2024-02-20 9:51 ` Christian Brauner 2024-01-29 13:53 ` [PATCH 0/2] netfs: Miscellaneous fixes Christian Brauner 2024-01-29 13:53 ` Christian Brauner
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