CIFS: Avoid returning EBUSY to upper layer VFS

From: Long Li <[email protected]>

EBUSY is not handled by VFS, and will be passed to user-mode. This is not correct as we need to wait for more credits.

This patch also fixes a bug where rsize or wsize is used uninitialized when the call to server->ops->wait_mtu_credits() fails.

Reported-by Dan Carpenter <[email protected]>

Signed-off-by Long Li <[email protected]>

---
 fs/cifs/file.c | 31 ++++++-------------------------
 1 file changed, 6 insertions(+), 25 deletions(-)

fs/cifs/file.c +6 -26

index 74c33d5..c9bc56b 100644
@@ -2541,14 +2541,13 @@ static int
 cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
        struct cifs_aio_ctx *ctx)
 {
-       int wait_retry = 0;
        unsigned int wsize, credits;
        int rc;
        struct TCP_Server_Info *server =
                tlink_tcon(wdata->cfile->tlink)->ses->server;
 
        /*
-        * Try to resend this wdata, waiting for credits up to 3 seconds.
+        * Wait for credits to resend this wdata.
         * Note: we are attempting to resend the whole wdata not in segments
         */
        do {

@@ -2556,19 +2555,13 @@ cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
                        server, wdata->bytes, &wsize, &credits);
 
                if (rc)
-                       break;
+                       goto out;
 
                if (wsize < wdata->bytes) {
                        add_credits_and_wake_if(server, credits, 0);
                        msleep(1000);
-                       wait_retry++;
                }
-       } while (wsize < wdata->bytes && wait_retry < 3);
-
-       if (wsize < wdata->bytes) {
-               rc = -EBUSY;
-               goto out;
-       }
+       } while (wsize < wdata->bytes);
 
        rc = -EAGAIN;
        while (rc == -EAGAIN) {

@@ -3234,14 +3227,13 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
                        struct list_head *rdata_list,
                        struct cifs_aio_ctx *ctx)
 {
-       int wait_retry = 0;
        unsigned int rsize, credits;
        int rc;
        struct TCP_Server_Info *server =
                tlink_tcon(rdata->cfile->tlink)->ses->server;
 
        /*
-        * Try to resend this rdata, waiting for credits up to 3 seconds.
+        * Wait for credits to resend this rdata.
         * Note: we are attempting to resend the whole rdata not in segments
         */
        do {

@@ -3249,24 +3241,13 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
                                                &rsize, &credits);
 
                if (rc)
-                       break;
+                       goto out;
 
                if (rsize < rdata->bytes) {
                        add_credits_and_wake_if(server, credits, 0);
                        msleep(1000);
-                       wait_retry++;
                }
-       } while (rsize < rdata->bytes && wait_retry < 3);
-
-       /*
-        * If we can't find enough credits to send this rdata
-        * release the rdata and return failure, this will pass
-        * whatever I/O amount we have finished to VFS.
-        */
-       if (rsize < rdata->bytes) {
-               rc = -EBUSY;
-               goto out;
-       }
+       } while (rsize < rdata->bytes);
 
        rc = -EAGAIN;
        while (rc == -EAGAIN) {
--

2.7.4

Tentatively pushed to cifs-2.6.git for-next

Quoted 101 lines · Long Li

From: Long Li <[email protected]>

EBUSY is not handled by VFS, and will be passed to user-mode. This is not correct as we need to wait for more credits.

This patch also fixes a bug where rsize or wsize is used uninitialized when the call to server->ops->wait_mtu_credits() fails.

Reported-by Dan Carpenter <[email protected]>

Signed-off-by Long Li <[email protected]>

---
 fs/cifs/file.c | 31 ++++++-------------------------
 1 file changed, 6 insertions(+), 25 deletions(-)

fs/cifs/file.c +6 -26

index 74c33d5..c9bc56b 100644
@@ -2541,14 +2541,13 @@ static int
 cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
        struct cifs_aio_ctx *ctx)
 {
-       int wait_retry = 0;
        unsigned int wsize, credits;
        int rc;
        struct TCP_Server_Info *server =
                tlink_tcon(wdata->cfile->tlink)->ses->server;
 
        /*
-        * Try to resend this wdata, waiting for credits up to 3 seconds.
+        * Wait for credits to resend this wdata.
         * Note: we are attempting to resend the whole wdata not in segments
         */
        do {

@@ -2556,19 +2555,13 @@ cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
                        server, wdata->bytes, &wsize, &credits);
 
                if (rc)
-                       break;
+                       goto out;
 
                if (wsize < wdata->bytes) {
                        add_credits_and_wake_if(server, credits, 0);
                        msleep(1000);
-                       wait_retry++;
                }
-       } while (wsize < wdata->bytes && wait_retry < 3);
-
-       if (wsize < wdata->bytes) {
-               rc = -EBUSY;
-               goto out;
-       }
+       } while (wsize < wdata->bytes);
 
        rc = -EAGAIN;
        while (rc == -EAGAIN) {

@@ -3234,14 +3227,13 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
                        struct list_head *rdata_list,
                        struct cifs_aio_ctx *ctx)
 {
-       int wait_retry = 0;
        unsigned int rsize, credits;
        int rc;
        struct TCP_Server_Info *server =
                tlink_tcon(rdata->cfile->tlink)->ses->server;
 
        /*
-        * Try to resend this rdata, waiting for credits up to 3 seconds.
+        * Wait for credits to resend this rdata.
         * Note: we are attempting to resend the whole rdata not in segments
         */
        do {

@@ -3249,24 +3241,13 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
                                                &rsize, &credits);
 
                if (rc)
-                       break;
+                       goto out;
 
                if (rsize < rdata->bytes) {
                        add_credits_and_wake_if(server, credits, 0);
                        msleep(1000);
-                       wait_retry++;
                }
-       } while (rsize < rdata->bytes && wait_retry < 3);
-
-       /*
-        * If we can't find enough credits to send this rdata
-        * release the rdata and return failure, this will pass
-        * whatever I/O amount we have finished to VFS.
-        */
-       if (rsize < rdata->bytes) {
-               rc = -EBUSY;
-               goto out;
-       }
+       } while (rsize < rdata->bytes);
 
        rc = -EAGAIN;
        while (rc == -EAGAIN) {
--

Quoted 2 lines

2.7.4

--
Thanks,

Steve