CIFS: store results of cifs_reopen_file to avoid infinite wait

[ Upstream commit 1fa839b4986d648b907d117275869a0e46c324b9 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 3f50cee79df9d3318209e19281acef536b34af37..fcf986aa2abe3e1b9f5f5e5c58962fa5325854d9 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2535,7 +2535,7 @@ 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) {
@@ -2948,7 +2948,7 @@ 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) {
@@ -3534,7 +3534,7 @@ 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);