Patch "ceph: fix readpage from fscache" has been added to the 4.12-stable tree

[<gregkh@linuxfoundation.org>]

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

    ceph: fix readpage from fscache

to the 4.12-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:
     ceph-fix-readpage-from-fscache.patch
and it can be found in the queue-4.12 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 dd2bc473482eedc60c29cf00ad12568ce40ce511 Mon Sep 17 00:00:00 2001
From: "Yan, Zheng" <zyan@redhat.com>
Date: Fri, 4 Aug 2017 11:22:31 +0800
Subject: ceph: fix readpage from fscache

From: Yan, Zheng <zyan@redhat.com>

commit dd2bc473482eedc60c29cf00ad12568ce40ce511 upstream.

ceph_readpage() unlocks page prematurely prematurely in the case
that page is reading from fscache. Caller of readpage expects that
page is uptodate when it get unlocked. So page shoule get locked
by completion callback of fscache_read_or_alloc_pages()

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ceph/addr.c  |   24 +++++++++++++++---------
 fs/ceph/cache.c |   12 +++---------
 2 files changed, 18 insertions(+), 18 deletions(-)

--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -189,7 +189,7 @@ static int ceph_releasepage(struct page
 /*
  * read a single page, without unlocking it.
  */
-static int readpage_nounlock(struct file *filp, struct page *page)
+static int ceph_do_readpage(struct file *filp, struct page *page)
 {
 	struct inode *inode = file_inode(filp);
 	struct ceph_inode_info *ci = ceph_inode(inode);
@@ -219,7 +219,7 @@ static int readpage_nounlock(struct file
 
 	err = ceph_readpage_from_fscache(inode, page);
 	if (err == 0)
-		goto out;
+		return -EINPROGRESS;
 
 	dout("readpage inode %p file %p page %p index %lu\n",
 	     inode, filp, page, page->index);
@@ -249,8 +249,11 @@ out:
 
 static int ceph_readpage(struct file *filp, struct page *page)
 {
-	int r = readpage_nounlock(filp, page);
-	unlock_page(page);
+	int r = ceph_do_readpage(filp, page);
+	if (r != -EINPROGRESS)
+		unlock_page(page);
+	else
+		r = 0;
 	return r;
 }
 
@@ -1240,7 +1243,7 @@ retry_locked:
 			goto retry_locked;
 		r = writepage_nounlock(page, NULL);
 		if (r < 0)
-			goto fail_nosnap;
+			goto fail_unlock;
 		goto retry_locked;
 	}
 
@@ -1268,11 +1271,14 @@ retry_locked:
 	}
 
 	/* we need to read it. */
-	r = readpage_nounlock(file, page);
-	if (r < 0)
-		goto fail_nosnap;
+	r = ceph_do_readpage(file, page);
+	if (r < 0) {
+		if (r == -EINPROGRESS)
+			return -EAGAIN;
+		goto fail_unlock;
+	}
 	goto retry_locked;
-fail_nosnap:
+fail_unlock:
 	unlock_page(page);
 	return r;
 }
--- a/fs/ceph/cache.c
+++ b/fs/ceph/cache.c
@@ -240,13 +240,7 @@ void ceph_fscache_file_set_cookie(struct
 	}
 }
 
-static void ceph_vfs_readpage_complete(struct page *page, void *data, int error)
-{
-	if (!error)
-		SetPageUptodate(page);
-}
-
-static void ceph_vfs_readpage_complete_unlock(struct page *page, void *data, int error)
+static void ceph_readpage_from_fscache_complete(struct page *page, void *data, int error)
 {
 	if (!error)
 		SetPageUptodate(page);
@@ -274,7 +268,7 @@ int ceph_readpage_from_fscache(struct in
 		return -ENOBUFS;
 
 	ret = fscache_read_or_alloc_page(ci->fscache, page,
-					 ceph_vfs_readpage_complete, NULL,
+					 ceph_readpage_from_fscache_complete, NULL,
 					 GFP_KERNEL);
 
 	switch (ret) {
@@ -303,7 +297,7 @@ int ceph_readpages_from_fscache(struct i
 		return -ENOBUFS;
 
 	ret = fscache_read_or_alloc_pages(ci->fscache, mapping, pages, nr_pages,
-					  ceph_vfs_readpage_complete_unlock,
+					  ceph_readpage_from_fscache_complete,
 					  NULL, mapping_gfp_mask(mapping));
 
 	switch (ret) {


Patches currently in stable-queue which might be from zyan@redhat.com are

queue-4.12/ceph-fix-readpage-from-fscache.patch