Patch "CIFS: store results of cifs_reopen_file to avoid infinite wait" has been added to the 4.4-stable tree

Patch "CIFS: store results of cifs_reopen_file to avoid infinite wait" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    CIFS: store results of cifs_reopen_file to avoid infinite wait

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     cifs-store-results-of-cifs_reopen_file-to-avoid-infinite-wait.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 1fa839b4986d648b907d117275869a0e46c324b9 Mon Sep 17 00:00:00 2001
From: Germano Percossi <germano.percossi@citrix.com>
Date: Fri, 7 Apr 2017 12:29:38 +0100
Subject: CIFS: store results of cifs_reopen_file to avoid infinite wait

From: Germano Percossi <germano.percossi@citrix.com>

commit 1fa839b4986d648b907d117275869a0e46c324b9 upstream.

This fixes Continuous Availability when errors during
file reopen are encountered.

cifs_user_readv and cifs_user_writev would wait for ever if
results of cifs_reopen_file are not stored and for later inspection.

In fact, results are checked and, in case of errors, a chain
of function calls leading to reads and writes to be scheduled in
a separate thread is skipped.
These threads will wake up the corresponding waiters once reads
and writes are done.

However, given the return value is not stored, when rc is checked
for errors a previous one (always zero) is inspected instead.
This leads to pending reads/writes added to the list, making
cifs_user_readv and cifs_user_writev wait for ever.

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/cifs/file.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2545,7 +2545,7 @@ cifs_write_from_iter(loff_t offset, size
 		wdata->credits = credits;
 
 		if (!wdata->cfile->invalidHandle ||
-		    !cifs_reopen_file(wdata->cfile, false))
+		    !(rc = cifs_reopen_file(wdata->cfile, false)))
 			rc = server->ops->async_writev(wdata,
 					cifs_uncached_writedata_release);
 		if (rc) {
@@ -2958,7 +2958,7 @@ cifs_send_async_read(loff_t offset, size
 		rdata->credits = credits;
 
 		if (!rdata->cfile->invalidHandle ||
-		    !cifs_reopen_file(rdata->cfile, true))
+		    !(rc = cifs_reopen_file(rdata->cfile, true)))
 			rc = server->ops->async_readv(rdata);
 error:
 		if (rc) {
@@ -3544,7 +3544,7 @@ static int cifs_readpages(struct file *f
 		}
 
 		if (!rdata->cfile->invalidHandle ||
-		    !cifs_reopen_file(rdata->cfile, true))
+		    !(rc = cifs_reopen_file(rdata->cfile, true)))
 			rc = server->ops->async_readv(rdata);
 		if (rc) {
 			add_credits_and_wake_if(server, rdata->credits, 0);


Patches currently in stable-queue which might be from germano.percossi@citrix.com are

queue-4.4/cifs-store-results-of-cifs_reopen_file-to-avoid-infinite-wait.patch