linux-kernel - [PATCH 4.9 81/92] CIFS: Force reval dentry if LOOKUP

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Date:   Wed, 16 Oct 2019 14:50:54 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Pavel Shilovsky <pshilov@...rosoft.com>,
        Steve French <stfrench@...rosoft.com>
Subject: [PATCH 4.9 81/92] CIFS: Force reval dentry if LOOKUP_REVAL flag is set

From: Pavel Shilovsky <piastryyy@...il.com>

commit 0b3d0ef9840f7be202393ca9116b857f6f793715 upstream.

Mark inode for force revalidation if LOOKUP_REVAL flag is set.
This tells the client to actually send a QueryInfo request to
the server to obtain the latest metadata in case a directory
or a file were changed remotely. Only do that if the client
doesn't have a lease for the file to avoid unneeded round
trips to the server.

Cc: <stable@...r.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@...rosoft.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/cifs/dir.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -830,10 +830,16 @@ lookup_out:
 static int
 cifs_d_revalidate(struct dentry *direntry, unsigned int flags)
 {
+	struct inode *inode;
+
 	if (flags & LOOKUP_RCU)
 		return -ECHILD;
 
 	if (d_really_is_positive(direntry)) {
+		inode = d_inode(direntry);
+		if ((flags & LOOKUP_REVAL) && !CIFS_CACHE_READ(CIFS_I(inode)))
+			CIFS_I(inode)->time = 0; /* force reval */
+
 		if (cifs_revalidate_dentry(direntry))
 			return 0;
 		else {
@@ -844,7 +850,7 @@ cifs_d_revalidate(struct dentry *direntr
 			 * attributes will have been updated by
 			 * cifs_revalidate_dentry().
 			 */
-			if (IS_AUTOMOUNT(d_inode(direntry)) &&
+			if (IS_AUTOMOUNT(inode) &&
 			   !(direntry->d_flags & DCACHE_NEED_AUTOMOUNT)) {
 				spin_lock(&direntry->d_lock);
 				direntry->d_flags |= DCACHE_NEED_AUTOMOUNT;