[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, 92 insertions, 20 deletions

diff --git a/fs/gfs2/ops_super.c b/fs/gfs2/ops_super.c
index 1c17acc..317d497 100644
--- a/fs/gfs2/ops_super.c
+++ b/fs/gfs2/ops_super.c
@@ -19,6 +19,7 @@
 #include <linux/kthread.h>
 #include <linux/delay.h>
 #include <linux/gfs2_ondisk.h>
+#include <linux/crc32.h>
 
 #include "gfs2.h"
 #include "lm_interface.h"
@@ -36,6 +37,10 @@
 #include "super.h"
 #include "sys.h"
 #include "util.h"
+#include "trans.h"
+#include "dir.h"
+#include "eattr.h"
+#include "bmap.h"
 
 /**
  * gfs2_write_inode - Make sure the inode is stable on the disk
@@ -47,12 +52,15 @@
 
 static int gfs2_write_inode(struct inode *inode, int sync)
 {
-	struct gfs2_inode *ip = inode->u.generic_ip;
-
-	if (current->flags & PF_MEMALLOC)
-		return 0;
-	if (ip && sync)
-		gfs2_log_flush(ip->i_gl->gl_sbd, ip->i_gl);
+	struct gfs2_inode *ip = GFS2_I(inode);
+
+	/* Check this is a "normal" inode */
+	if (inode->u.generic_ip) {
+		if (current->flags & PF_MEMALLOC)
+			return 0;
+		if (sync)
+			gfs2_log_flush(ip->i_gl->gl_sbd, ip->i_gl);
+	}
 
 	return 0;
 }
@@ -78,7 +86,6 @@ static void gfs2_put_super(struct super_block *sb)
 		gfs2_glock_dq_uninit(&sdp->sd_freeze_gh);
 	mutex_unlock(&sdp->sd_freeze_lock);
 
-	kthread_stop(sdp->sd_inoded_process);
 	kthread_stop(sdp->sd_quotad_process);
 	kthread_stop(sdp->sd_logd_process);
 	kthread_stop(sdp->sd_recoverd_process);
@@ -110,11 +117,9 @@ static void gfs2_put_super(struct super_block *sb)
 		gfs2_glock_dq_uninit(&sdp->sd_jinode_gh);
 		gfs2_glock_dq_uninit(&sdp->sd_ir_gh);
 		gfs2_glock_dq_uninit(&sdp->sd_sc_gh);
-		gfs2_glock_dq_uninit(&sdp->sd_ut_gh);
 		gfs2_glock_dq_uninit(&sdp->sd_qc_gh);
 		iput(sdp->sd_ir_inode);
 		iput(sdp->sd_sc_inode);
-		iput(sdp->sd_ut_inode);
 		iput(sdp->sd_qc_inode);
 	}
 
@@ -274,16 +279,20 @@ static int gfs2_remount_fs(struct super_block *sb, int *flags, char *data)
 
 static void gfs2_clear_inode(struct inode *inode)
 {
-	struct gfs2_inode *ip = inode->u.generic_ip;
-
-	if (ip) {
-		spin_lock(&ip->i_spin);
-		ip->i_vnode = NULL;
-		inode->u.generic_ip = NULL;
-		spin_unlock(&ip->i_spin);
-
+	/* This tells us its a "real" inode and not one which only
+	 * serves to contain an address space (see rgrp.c, meta_io.c)
+	 * which therefore doesn't have its own glocks.
+	 */
+	if (inode->u.generic_ip) {
+		struct gfs2_inode *ip = GFS2_I(inode);
+		gfs2_glock_inode_squish(inode);
+		gfs2_assert(inode->i_sb->s_fs_info, ip->i_gl->gl_state == LM_ST_UNLOCKED);
+		ip->i_gl->gl_object = NULL;
 		gfs2_glock_schedule_for_reclaim(ip->i_gl);
-		gfs2_inode_put(ip);
+		gfs2_glock_put(ip->i_gl);
+		ip->i_gl = NULL;
+		if (ip->i_iopen_gh.gh_gl)
+			gfs2_glock_dq_uninit(&ip->i_iopen_gh);
 	}
 }
 
@@ -361,6 +370,70 @@ static int gfs2_show_options(struct seq_file *s, struct vfsmount *mnt)
 	return 0;
 }
 
+/* 
+ * We have to (at the moment) hold the inodes main lock to cover
+ * the gap between unlocking the shared lock on the iopen lock and
+ * taking the exclusive lock. I'd rather do a shared -> exclusive
+ * conversion on the iopen lock, but we can change that later. This
+ * is safe, just less efficient.
+ */
+static void gfs2_delete_inode(struct inode *inode)
+{
+	struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_holder gh;
+	int error;
+
+	if (!inode->u.generic_ip)
+		goto out;
+
+	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, LM_FLAG_TRY_1CB | GL_NOCACHE, &gh);
+	if (unlikely(error)) {
+		gfs2_glock_dq_uninit(&ip->i_iopen_gh);
+		goto out;
+	}
+
+	gfs2_glock_dq(&ip->i_iopen_gh);
+	gfs2_holder_reinit(LM_ST_EXCLUSIVE, LM_FLAG_TRY_1CB | GL_NOCACHE, &ip->i_iopen_gh);
+	error = gfs2_glock_nq(&ip->i_iopen_gh);
+	if (error)
+		goto out_uninit;
+
+	if (S_ISDIR(ip->i_di.di_mode) &&
+	    (ip->i_di.di_flags & GFS2_DIF_EXHASH)) {
+		error = gfs2_dir_exhash_dealloc(ip);
+		if (error)
+			goto out_unlock;
+	}
+
+	if (ip->i_di.di_eattr) {
+		error = gfs2_ea_dealloc(ip);
+		if (error)
+			goto out_unlock;
+	}
+
+	if (!gfs2_is_stuffed(ip)) {
+		error = gfs2_file_dealloc(ip);
+		if (error)
+			goto out_unlock;
+	}
+
+	error = gfs2_dinode_dealloc(ip);
+
+out_unlock:
+	gfs2_glock_dq(&ip->i_iopen_gh);
+out_uninit:
+	gfs2_holder_uninit(&ip->i_iopen_gh);
+	gfs2_glock_dq_uninit(&gh);
+	if (error)
+		fs_warn(sdp, "gfs2_delete_inode: %d\n", error);
+out:
+	truncate_inode_pages(&inode->i_data, 0);
+	clear_inode(inode);
+}
+
+
+
 static struct inode *gfs2_alloc_inode(struct super_block *sb)
 {
 	struct gfs2_sbd *sdp = sb->s_fs_info;
@@ -370,8 +443,6 @@ static struct inode *gfs2_alloc_inode(struct super_block *sb)
 	if (ip) {
 		ip->i_flags = 0;
 		ip->i_gl = NULL;
-		ip->i_sbd = sdp;
-		ip->i_vnode = &ip->i_inode;
 		ip->i_greedy = gfs2_tune_get(sdp, gt_greedy_default);
 		ip->i_last_pfault = jiffies;
 	}
@@ -387,6 +458,7 @@ struct super_operations gfs2_super_ops = {
 	.alloc_inode = gfs2_alloc_inode,
 	.destroy_inode = gfs2_destroy_inode,
 	.write_inode = gfs2_write_inode,
+	.delete_inode = gfs2_delete_inode,
 	.put_super = gfs2_put_super,
 	.write_super = gfs2_write_super,
 	.write_super_lockfs = gfs2_write_super_lockfs,