CIFS: store results of cifs_reopen_file to avoid infinite wait

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>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Steve French <smfrench@gmail.com>

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index aa3debbba82648944a1e1426516abebb268b7ca0..21d4045357397de647b8fe0282ed1a436b7e3a7f 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2597,7 +2597,7 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
                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) {
@@ -3022,7 +3022,7 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
                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) {
@@ -3617,7 +3617,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                }
 
                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);