CIFS: Fix read after write for files with read caching
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Message ID 1551750481-17919-1-git-send-email-pshilov@microsoft.com
State New
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Series
  • CIFS: Fix read after write for files with read caching
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Commit Message

Pavel Shilovsky March 5, 2019, 1:48 a.m. UTC
When we have a READ lease for a file and have just issued a write
operation to the server we need to purge the cache and set oplock/lease
level to NONE to avoid reading stale data. Currently we do that
only if a write operation succedeed thus not covering cases when
a request was sent to the server but a negative error code was
returned later for some other reasons (e.g. -EIOCBQUEUED or -EINTR).
Fix this by turning off caching regardless of the error code being
returned.

The patches fixes generic tests 075 and 112 from the xfs-tests.

Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
---
 fs/cifs/file.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

Comments

ronnie sahlberg March 5, 2019, 2:37 a.m. UTC | #1
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>

On Tue, Mar 5, 2019 at 11:48 AM Pavel Shilovsky <piastryyy@gmail.com> wrote:
>
> When we have a READ lease for a file and have just issued a write
> operation to the server we need to purge the cache and set oplock/lease
> level to NONE to avoid reading stale data. Currently we do that
> only if a write operation succedeed thus not covering cases when
> a request was sent to the server but a negative error code was
> returned later for some other reasons (e.g. -EIOCBQUEUED or -EINTR).
> Fix this by turning off caching regardless of the error code being
> returned.
>
> The patches fixes generic tests 075 and 112 from the xfs-tests.
>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
> ---
>  fs/cifs/file.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index 9b53f33..4c144c1 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -3096,14 +3096,16 @@ cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from)
>          * these pages but not on the region from pos to ppos+len-1.
>          */
>         written = cifs_user_writev(iocb, from);
> -       if (written > 0 && CIFS_CACHE_READ(cinode)) {
> +       if (CIFS_CACHE_READ(cinode)) {
>                 /*
> -                * Windows 7 server can delay breaking level2 oplock if a write
> -                * request comes - break it on the client to prevent reading
> -                * an old data.
> +                * We have read level caching and we have just sent a write
> +                * request to the server thus making data in the cache stale.
> +                * Zap the cache and set oplock/lease level to NONE to avoid
> +                * reading stale data from the cache. All subsequent read
> +                * operations will read new data from the server.
>                  */
>                 cifs_zap_mapping(inode);
> -               cifs_dbg(FYI, "Set no oplock for inode=%p after a write operation\n",
> +               cifs_dbg(FYI, "Set Oplock/Lease to NONE for inode=%p after write\n",
>                          inode);
>                 cinode->oplock = 0;
>         }
> --
> 2.7.4
>

Patch
diff mbox series

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 9b53f33..4c144c1 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3096,14 +3096,16 @@  cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from)
 	 * these pages but not on the region from pos to ppos+len-1.
 	 */
 	written = cifs_user_writev(iocb, from);
-	if (written > 0 && CIFS_CACHE_READ(cinode)) {
+	if (CIFS_CACHE_READ(cinode)) {
 		/*
-		 * Windows 7 server can delay breaking level2 oplock if a write
-		 * request comes - break it on the client to prevent reading
-		 * an old data.
+		 * We have read level caching and we have just sent a write
+		 * request to the server thus making data in the cache stale.
+		 * Zap the cache and set oplock/lease level to NONE to avoid
+		 * reading stale data from the cache. All subsequent read
+		 * operations will read new data from the server.
 		 */
 		cifs_zap_mapping(inode);
-		cifs_dbg(FYI, "Set no oplock for inode=%p after a write operation\n",
+		cifs_dbg(FYI, "Set Oplock/Lease to NONE for inode=%p after write\n",
 			 inode);
 		cinode->oplock = 0;
 	}