[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, 24 insertions, 36 deletions

diff --git a/fs/gfs2/ops_export.c b/fs/gfs2/ops_export.c
index a376ead7d0cd..eacc1c092f91 100644
--- a/fs/gfs2/ops_export.c
+++ b/fs/gfs2/ops_export.c
@@ -66,7 +66,7 @@ static int gfs2_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
 {
         struct inode *inode = dentry->d_inode;
         struct super_block *sb = inode->i_sb;
-        struct gfs2_inode *ip = inode->u.generic_ip;
+        struct gfs2_inode *ip = GFS2_I(inode);
 
         if (*len < 4 || (connectable && *len < 8))
                 return 255;
@@ -86,8 +86,8 @@ static int gfs2_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
 
         spin_lock(&dentry->d_lock);
         inode = dentry->d_parent->d_inode;
-        ip = inode->u.generic_ip;
-        gfs2_inode_hold(ip);
+        ip = GFS2_I(inode);
+        igrab(inode);
         spin_unlock(&dentry->d_lock);
 
         fh[4] = ip->i_num.no_formal_ino >> 32;
@@ -100,7 +100,7 @@ static int gfs2_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
         fh[7] = cpu_to_be32(fh[7]);
         *len = 8;
 
-        gfs2_inode_put(ip);
+        iput(inode);
 
         return *len;
 }
@@ -142,8 +142,8 @@ static int gfs2_get_name(struct dentry *parent, char *name,
         if (!S_ISDIR(dir->i_mode) || !inode)
                 return -EINVAL;
 
-        dip = dir->u.generic_ip;
-        ip = inode->u.generic_ip;
+        dip = GFS2_I(dir);
+        ip = GFS2_I(inode);
 
         *name = 0;
         gnfd.inum = ip->i_num;
@@ -189,39 +189,30 @@ static struct dentry *gfs2_get_parent(struct dentry *child)
 static struct dentry *gfs2_get_dentry(struct super_block *sb, void *inum_p)
 {
         struct gfs2_sbd *sdp = sb->s_fs_info;
-        struct gfs2_inum *inum = (struct gfs2_inum *)inum_p;
+        struct gfs2_inum *inum = inum_p;
         struct gfs2_holder i_gh, ri_gh, rgd_gh;
         struct gfs2_rgrpd *rgd;
-        struct gfs2_inode *ip;
         struct inode *inode;
         struct dentry *dentry;
         int error;
 
         /* System files? */
 
-        inode = gfs2_iget(sb, inum);
+        inode = gfs2_ilookup(sb, inum);
         if (inode) {
-                ip = inode->u.generic_ip;
-                if (ip->i_num.no_formal_ino != inum->no_formal_ino) {
+                if (GFS2_I(inode)->i_num.no_formal_ino != inum->no_formal_ino) {
                         iput(inode);
                         return ERR_PTR(-ESTALE);
                 }
                 goto out_inode;
         }
 
-        error = gfs2_glock_nq_num(sdp,
-                                  inum->no_addr, &gfs2_inode_glops,
+        error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
                                   LM_ST_SHARED, LM_FLAG_ANY | GL_LOCAL_EXCL,
                                   &i_gh);
         if (error)
                 return ERR_PTR(error);
 
-        error = gfs2_inode_get(i_gh.gh_gl, inum, NO_CREATE, &ip);
-        if (error)
-                goto fail;
-        if (ip)
-                goto out_ip;
-
         error = gfs2_rindex_hold(sdp, &ri_gh);
         if (error)
                 goto fail;
@@ -242,32 +233,29 @@ static struct dentry *gfs2_get_dentry(struct super_block *sb, void *inum_p)
         gfs2_glock_dq_uninit(&rgd_gh);
         gfs2_glock_dq_uninit(&ri_gh);
 
-        error = gfs2_inode_get(i_gh.gh_gl, inum, CREATE, &ip);
-        if (error)
+        inode = gfs2_inode_lookup(sb, inum, DT_UNKNOWN);
+        if (!inode)
+                goto fail;
+        if (IS_ERR(inode)) {
+                error = PTR_ERR(inode);
                 goto fail;
+        }
 
-        error = gfs2_inode_refresh(ip);
+        error = gfs2_inode_refresh(GFS2_I(inode));
         if (error) {
-                gfs2_inode_put(ip);
+                iput(inode);
                 goto fail;
         }
 
- out_ip:
         error = -EIO;
-        if (ip->i_di.di_flags & GFS2_DIF_SYSTEM) {
-                gfs2_inode_put(ip);
+        if (GFS2_I(inode)->i_di.di_flags & GFS2_DIF_SYSTEM) {
+                iput(inode);
                 goto fail;
         }
 
         gfs2_glock_dq_uninit(&i_gh);
 
-        inode = gfs2_ip2v(ip);
-        gfs2_inode_put(ip);
-
-        if (!inode)
-                return ERR_PTR(-ENOMEM);
-
- out_inode:
+out_inode:
         dentry = d_alloc_anon(inode);
         if (!dentry) {
                 iput(inode);
@@ -276,13 +264,13 @@ static struct dentry *gfs2_get_dentry(struct super_block *sb, void *inum_p)
 
         return dentry;
 
- fail_rgd:
+fail_rgd:
         gfs2_glock_dq_uninit(&rgd_gh);
 
- fail_rindex:
+fail_rindex:
         gfs2_glock_dq_uninit(&ri_gh);
 
- fail:
+fail:
         gfs2_glock_dq_uninit(&i_gh);
         return ERR_PTR(error);
 }