[GFS2] Fix unlinked file handling

This patch fixes the way we have been dealing with unlinked,
but still open files. It removes all limits (other than memory
for inodes, as per every other filesystem) on numbers of these
which we can support on GFS2. It also means that (like other
fs) its the responsibility of the last process to close the file
to deallocate the storage, rather than the person who did the
unlinking. Note that with GFS2, those two events might take place
on different nodes.

Also there are a number of other changes:

 o We use the Linux inode subsystem as it was intended to be
used, wrt allocating GFS2 inodes
 o The Linux inode cache is now the point which we use for
local enforcement of only holding one copy of the inode in
core at once (previous to this we used the glock layer).
 o We no longer use the unlinked "special" file. We just ignore it
completely. This makes unlinking more efficient.
 o We now use the 4th block allocation state. The previously unused
state is used to track unlinked but still open inodes.
 o gfs2_inoded is no longer needed
 o Several fields are now no longer needed (and removed) from the in
core struct gfs2_inode
 o Several fields are no longer needed (and removed) from the in core
superblock

There are a number of future possible optimisations and clean ups
which have been made possible by this patch.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 21 insertions, 81 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 0603a6de52c9..35bac90878a5 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -654,7 +654,7 @@ static void run_queue(struct gfs2_glock *gl)
  * Gives caller exclusive access to manipulate a glock structure.
  */
 
-void gfs2_glmutex_lock(struct gfs2_glock *gl)
+static void gfs2_glmutex_lock(struct gfs2_glock *gl)
 {
 	struct gfs2_holder gh;
 
@@ -704,7 +704,7 @@ static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
  *
  */
 
-void gfs2_glmutex_unlock(struct gfs2_glock *gl)
+static void gfs2_glmutex_unlock(struct gfs2_glock *gl)
 {
 	spin_lock(&gl->gl_spin);
 	clear_bit(GLF_LOCK, &gl->gl_flags);
@@ -726,7 +726,7 @@ static void handle_callback(struct gfs2_glock *gl, unsigned int state)
 {
 	struct gfs2_holder *gh, *new_gh = NULL;
 
- restart:
+restart:
 	spin_lock(&gl->gl_spin);
 
 	list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
@@ -752,13 +752,27 @@ static void handle_callback(struct gfs2_glock *gl, unsigned int state)
 		goto restart;
 	}
 
- out:
+out:
 	spin_unlock(&gl->gl_spin);
 
 	if (new_gh)
 		gfs2_holder_put(new_gh);
 }
 
+void gfs2_glock_inode_squish(struct inode *inode)
+{
+	struct gfs2_holder gh;
+	struct gfs2_glock *gl = GFS2_I(inode)->i_gl;
+	gfs2_holder_init(gl, LM_ST_UNLOCKED, 0, &gh);
+	set_bit(HIF_DEMOTE, &gh.gh_iflags);
+	spin_lock(&gl->gl_spin);
+	gfs2_assert(inode->i_sb->s_fs_info, list_empty(&gl->gl_holders));
+	list_add_tail(&gh.gh_list, &gl->gl_waiters2);
+	run_queue(gl);
+	spin_unlock(&gl->gl_spin);
+	gfs2_holder_uninit(&gh);
+}
+
 /**
  * state_change - record that the glock is now in a different state
  * @gl: the glock
@@ -1383,8 +1397,7 @@ int gfs2_glock_be_greedy(struct gfs2_glock *gl, unsigned int time)
 	struct greedy *gr;
 	struct gfs2_holder *gh;
 
-	if (!time ||
-	    gl->gl_sbd->sd_args.ar_localcaching ||
+	if (!time || gl->gl_sbd->sd_args.ar_localcaching ||
 	    test_and_set_bit(GLF_GREEDY, &gl->gl_flags))
 		return 1;
 
@@ -1785,43 +1798,6 @@ void gfs2_glock_cb(lm_fsdata_t *fsdata, unsigned int type, void *data)
 }
 
 /**
- * gfs2_try_toss_inode - try to remove a particular inode struct from cache
- * sdp: the filesystem
- * inum: the inode number
- *
- */
-
-void gfs2_try_toss_inode(struct gfs2_sbd *sdp, struct gfs2_inum *inum)
-{
-	struct gfs2_glock *gl;
-	struct gfs2_inode *ip;
-	int error;
-
-	error = gfs2_glock_get(sdp, inum->no_addr, &gfs2_inode_glops,
-			       NO_CREATE, &gl);
-	if (error || !gl)
-		return;
-
-	if (!gfs2_glmutex_trylock(gl))
-		goto out;
-
-	ip = gl->gl_object;
-	if (!ip)
-		goto out_unlock;
-
-	if (atomic_read(&ip->i_count))
-		goto out_unlock;
-
-	gfs2_inode_destroy(ip, 1);
-
- out_unlock:
-	gfs2_glmutex_unlock(gl);
-
- out:
-	gfs2_glock_put(gl);
-}
-
-/**
  * gfs2_iopen_go_callback - Try to kick the inode/vnode associated with an
  *                          iopen glock from memory
  * @io_gl: the iopen glock
@@ -1831,34 +1807,10 @@ void gfs2_try_toss_inode(struct gfs2_sbd *sdp, struct gfs2_inum *inum)
 
 void gfs2_iopen_go_callback(struct gfs2_glock *io_gl, unsigned int state)
 {
-	struct gfs2_glock *i_gl;
 
 	if (state != LM_ST_UNLOCKED)
 		return;
-
-	spin_lock(&io_gl->gl_spin);
-	i_gl = io_gl->gl_object;
-	if (i_gl) {
-		gfs2_glock_hold(i_gl);
-		spin_unlock(&io_gl->gl_spin);
-	} else {
-		spin_unlock(&io_gl->gl_spin);
-		return;
-	}
-
-	if (gfs2_glmutex_trylock(i_gl)) {
-		struct gfs2_inode *ip = i_gl->gl_object;
-		if (ip) {
-			gfs2_try_toss_vnode(ip);
-			gfs2_glmutex_unlock(i_gl);
-			gfs2_glock_schedule_for_reclaim(i_gl);
-			goto out;
-		}
-		gfs2_glmutex_unlock(i_gl);
-	}
-
- out:
-	gfs2_glock_put(i_gl);
+	/* FIXME: remove this? */
 }
 
 /**
@@ -1935,11 +1887,6 @@ void gfs2_reclaim_glock(struct gfs2_sbd *sdp)
 	atomic_inc(&sdp->sd_reclaimed);
 
 	if (gfs2_glmutex_trylock(gl)) {
-		if (gl->gl_ops == &gfs2_inode_glops) {
-			struct gfs2_inode *ip = gl->gl_object;
-			if (ip && !atomic_read(&ip->i_count))
-				gfs2_inode_destroy(ip, 1);
-		}
 		if (queue_empty(gl, &gl->gl_holders) &&
 		    gl->gl_state != LM_ST_UNLOCKED &&
 		    demote_ok(gl))
@@ -2018,7 +1965,7 @@ static void scan_glock(struct gfs2_glock *gl)
 	if (gfs2_glmutex_trylock(gl)) {
 		if (gl->gl_ops == &gfs2_inode_glops) {
 			struct gfs2_inode *ip = gl->gl_object;
-			if (ip && !atomic_read(&ip->i_count))
+			if (ip)
 				goto out_schedule;
 		}
 		if (queue_empty(gl, &gl->gl_holders) &&
@@ -2078,11 +2025,6 @@ static void clear_glock(struct gfs2_glock *gl)
 	}
 
 	if (gfs2_glmutex_trylock(gl)) {
-		if (gl->gl_ops == &gfs2_inode_glops) {
-			struct gfs2_inode *ip = gl->gl_object;
-			if (ip && !atomic_read(&ip->i_count))
-				gfs2_inode_destroy(ip, 1);
-		}
 		if (queue_empty(gl, &gl->gl_holders) &&
 		    gl->gl_state != LM_ST_UNLOCKED)
 			handle_callback(gl, LM_ST_UNLOCKED);
@@ -2199,13 +2141,11 @@ static int dump_inode(struct gfs2_inode *ip)
 		    (unsigned long long)ip->i_num.no_formal_ino,
 		    (unsigned long long)ip->i_num.no_addr);
 	printk(KERN_INFO "    type = %u\n", IF2DT(ip->i_di.di_mode));
-	printk(KERN_INFO "    i_count = %d\n", atomic_read(&ip->i_count));
 	printk(KERN_INFO "    i_flags =");
 	for (x = 0; x < 32; x++)
 		if (test_bit(x, &ip->i_flags))
 			printk(" %u", x);
 	printk(" \n");
-	printk(KERN_INFO "    vnode = %s\n", (ip->i_vnode) ? "yes" : "no");
 
 	error = 0;