master - gfs-kernel: GFS: madvise system call causes assertion

[Abhijith Das <adas at fedoraproject dot org>]

Gitweb:        http://git.fedorahosted.org/git/cluster.git?p=cluster.git;a=commitdiff;h=7e37afc2a65961954c5ff470fd4cd284017253da
Commit:        7e37afc2a65961954c5ff470fd4cd284017253da
Parent:        0f9f1414b6eb6f17b272b4aee393ed00f5a1c329
Author:        Abhijith Das <adas@redhat.com>
AuthorDate:    Thu Oct 2 13:07:44 2008 -0500
Committer:     Abhijith Das <adas@redhat.com>
CommitterDate: Thu Oct 2 13:10:52 2008 -0500

gfs-kernel: GFS: madvise system call causes assertion

Since the madvise system call was enabled by the patch to bug 429343, it's
possible for a inode glock holder to never get dequeued through gfs_readpage.
This causes an assertion (bug 464837)

GFS: fsid=cl102a:gfs1.1: warning: assertion "(gh->gh_flags & LM_FLAG_ANY) ||
(tmp_gh->gh_flags & LM_FLAG_ANY)" failed
GFS: fsid=cl102a:gfs1.1: function = add_to_queue
GFS: fsid=cl102a:gfs1.1: file =
/builddir/build/BUILD/gfs-kmod-0.1.23/_kmod_build_/src/gfs/glock.c, line = 1418
GFS: fsid=cl102a:gfs1.1: time = 1222739610

This patch reverts the patch to bz 429343. Don't log any warnings/errors and
simply return ENOSYS when you arrive at gfs_readpage without the inode glock
held. (madvise syscall case)
---
 gfs-kernel/src/gfs/glock.h       |   15 ++++++++-------
 gfs-kernel/src/gfs/ops_address.c |   29 ++---------------------------
 2 files changed, 10 insertions(+), 34 deletions(-)

diff --git a/gfs-kernel/src/gfs/glock.h b/gfs-kernel/src/gfs/glock.h
index 198dc39..a0342b1 100644
--- a/gfs-kernel/src/gfs/glock.h
+++ b/gfs-kernel/src/gfs/glock.h
@@ -20,17 +20,17 @@
 #define GL_NOCACHE        (0x00000400) /* Release glock when done, don't cache */
 #define GL_SYNC           (0x00000800) /* Sync to disk when no more holders */
 #define GL_NOCANCEL       (0x00001000) /* Don't ever cancel this request */
-#define GL_READPAGE       (0x00002000) /* gfs_readpage() issued this lock request */
 #define GL_NOCANCEL_OTHER (0x00004000) /* Don't cancel other locks for this */
 
 #define GLR_TRYFAILED     (13)
 #define GLR_CANCELED      (14)
 
-static __inline__ struct gfs_holder*
+static __inline__ int
 gfs_glock_is_locked_by_me(struct gfs_glock *gl)
 {
 	struct list_head *tmp, *head;
 	struct gfs_holder *gh;
+	int locked = FALSE;
 
 	/* Look in glock's list of holders for one with current task as owner */
 	spin_lock(&gl->gl_spin);
@@ -38,13 +38,14 @@ gfs_glock_is_locked_by_me(struct gfs_glock *gl)
 	     tmp != head;
 	     tmp = tmp->next) {
 		gh = list_entry(tmp, struct gfs_holder, gh_list);
-		if (gh->gh_owner == current)
-			goto out;
+		if (gh->gh_owner == current) {
+			locked = TRUE;
+			break;
+		}
 	}
-	gh = NULL;
-out:
 	spin_unlock(&gl->gl_spin);
-	return gh;
+
+	return locked;
 }
 static __inline__ int
 gfs_glock_is_held_excl(struct gfs_glock *gl)
diff --git a/gfs-kernel/src/gfs/ops_address.c b/gfs-kernel/src/gfs/ops_address.c
index 0fb4d6a..98c3384 100644
--- a/gfs-kernel/src/gfs/ops_address.c
+++ b/gfs-kernel/src/gfs/ops_address.c
@@ -259,33 +259,13 @@ gfs_readpage(struct file *file, struct page *page)
 {
 	struct gfs_inode *ip = get_v2ip(page->mapping->host);
 	struct gfs_sbd *sdp = ip->i_sbd;
-	struct gfs_holder *gh;
 	int error;
 
 	atomic_inc(&sdp->sd_ops_address);
 
-	/* When gfs_readpage is called from the sys_madvise code through the 
-	 * readahead code, the inode glock is not held. In this case, we hold 
-	 * the inode glock, unlock the page and return AOP_TRUNCATED_PAGE. The
-	 * caller will then reload the page and call gfs_readpage again. We 
-	 * also add the flag GL_READPAGE to denote that the glock was held in
-	 * this function and if so, we unlock it before leaving this function
-	 */
-	gh = gfs_glock_is_locked_by_me(ip->i_gl);
-	if (!gh) {
-		gh = kmalloc(sizeof(struct gfs_holder), GFP_NOFS);
-		if (!gh)
-			return -ENOBUFS;
-		gfs_holder_init(ip->i_gl, LM_ST_SHARED, 
-				GL_READPAGE | LM_FLAG_ANY, gh);
+	if (!gfs_glock_is_locked_by_me(ip->i_gl)) {
 		unlock_page(page);
-		error = gfs_glock_nq(gh);
-		if (error) {
-			gfs_holder_uninit(gh);
-			kfree(gh);
-			goto out;
-		}
-		return AOP_TRUNCATED_PAGE;
+		return -ENOSYS;
 	}
 
 	if (!gfs_is_jdata(ip)) {
@@ -300,11 +280,6 @@ gfs_readpage(struct file *file, struct page *page)
 	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 		error = -EIO;
 
-	if (gh->gh_flags & GL_READPAGE) { /* If we grabbed the glock here */
-		gfs_glock_dq_uninit(gh);
-		kfree(gh);
-	}
-out:
 	return error;
 }