[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, 13 insertions, 17 deletions

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index e4c75a74df5b..a76f1a778920 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -184,8 +184,7 @@ static void buf_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
 static void buf_lo_before_scan(struct gfs2_jdesc *jd,
 			       struct gfs2_log_header *head, int pass)
 {
-	struct gfs2_inode *ip = jd->jd_inode->u.generic_ip;
-	struct gfs2_sbd *sdp = ip->i_sbd;
+	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 
 	if (pass != 0)
 		return;
@@ -198,8 +197,8 @@ static int buf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 				struct gfs2_log_descriptor *ld, __be64 *ptr,
 				int pass)
 {
-	struct gfs2_inode *ip = jd->jd_inode->u.generic_ip;
-	struct gfs2_sbd *sdp = ip->i_sbd;
+	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
+	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 	struct gfs2_glock *gl = ip->i_gl;
 	unsigned int blks = be32_to_cpu(ld->ld_data1);
 	struct buffer_head *bh_log, *bh_ip;
@@ -245,8 +244,8 @@ static int buf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 
 static void buf_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
 {
-	struct gfs2_inode *ip = jd->jd_inode->u.generic_ip;
-	struct gfs2_sbd *sdp = ip->i_sbd;
+	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
+	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 
 	if (error) {
 		gfs2_meta_sync(ip->i_gl,
@@ -332,8 +331,7 @@ static void revoke_lo_before_commit(struct gfs2_sbd *sdp)
 static void revoke_lo_before_scan(struct gfs2_jdesc *jd,
 				  struct gfs2_log_header *head, int pass)
 {
-	struct gfs2_inode *ip = jd->jd_inode->u.generic_ip;
-	struct gfs2_sbd *sdp = ip->i_sbd;
+	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 
 	if (pass != 0)
 		return;
@@ -346,8 +344,7 @@ static int revoke_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 				   struct gfs2_log_descriptor *ld, __be64 *ptr,
 				   int pass)
 {
-	struct gfs2_inode *ip = jd->jd_inode->u.generic_ip;
-	struct gfs2_sbd *sdp = ip->i_sbd;
+	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 	unsigned int blks = be32_to_cpu(ld->ld_length);
 	unsigned int revokes = be32_to_cpu(ld->ld_data1);
 	struct buffer_head *bh;
@@ -393,8 +390,7 @@ static int revoke_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 
 static void revoke_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
 {
-	struct gfs2_inode *ip = jd->jd_inode->u.generic_ip;
-	struct gfs2_sbd *sdp = ip->i_sbd;
+	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 
 	if (error) {
 		gfs2_revoke_clean(sdp);
@@ -465,7 +461,7 @@ static void databuf_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
 	struct gfs2_bufdata *bd = container_of(le, struct gfs2_bufdata, bd_le);
 	struct gfs2_trans *tr = current->journal_info;
 	struct address_space *mapping = bd->bd_bh->b_page->mapping;
-	struct gfs2_inode *ip = mapping->host->u.generic_ip;
+	struct gfs2_inode *ip = GFS2_I(mapping->host);
 
 	tr->tr_touched = 1;
 	if (!list_empty(&bd->bd_list_tr) &&
@@ -665,8 +661,8 @@ static int databuf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 				    struct gfs2_log_descriptor *ld,
 				    __be64 *ptr, int pass)
 {
-	struct gfs2_inode *ip = jd->jd_inode->u.generic_ip;
-	struct gfs2_sbd *sdp = ip->i_sbd;
+	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
+	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 	struct gfs2_glock *gl = ip->i_gl;
 	unsigned int blks = be32_to_cpu(ld->ld_data1);
 	struct buffer_head *bh_log, *bh_ip;
@@ -716,8 +712,8 @@ static int databuf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 
 static void databuf_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
 {
-	struct gfs2_inode *ip = jd->jd_inode->u.generic_ip;
-	struct gfs2_sbd *sdp = ip->i_sbd;
+	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
+	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 
 	if (error) {
 		gfs2_meta_sync(ip->i_gl,