[JFFS2] Track parent inode for directories (for NFS export)

To support NFS export, we need to know the parent inode of directories.
Rather than growing the jffs2_inode_cache structure, share space with
the nlink field -- which was always set to 1 for directories anyway.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

12 files changed, 70 insertions, 42 deletions

diff --git a/fs/jffs2/build.c b/fs/jffs2/build.c
index d58f845ccb8..c5e1450d79f 100644
--- a/fs/jffs2/build.c
+++ b/fs/jffs2/build.c
@@ -46,7 +46,7 @@ next_inode(int *i, struct jffs2_inode_cache *ic, struct jffs2_sb_info *c)
 
 
 static void jffs2_build_inode_pass1(struct jffs2_sb_info *c,
-                                        struct jffs2_inode_cache *ic)
+                                    struct jffs2_inode_cache *ic)
 {
         struct jffs2_full_dirent *fd;
 
@@ -68,11 +68,17 @@ static void jffs2_build_inode_pass1(struct jffs2_sb_info *c,
                         continue;
                 }
 
-                if (child_ic->nlink++ && fd->type == DT_DIR) {
-                        JFFS2_ERROR("child dir \"%s\" (ino #%u) of dir ino #%u appears to be a hard link\n",
-                                fd->name, fd->ino, ic->ino);
-                        /* TODO: What do we do about it? */
-                }
+                if (fd->type == DT_DIR) {
+                        if (child_ic->pino_nlink) {
+                                JFFS2_ERROR("child dir \"%s\" (ino #%u) of dir ino #%u appears to be a hard link\n",
+                                            fd->name, fd->ino, ic->ino);
+                                /* TODO: What do we do about it? */
+                        } else {
+                                child_ic->pino_nlink = ic->ino;
+                        }
+                } else
+                        child_ic->pino_nlink++;
+
                 dbg_fsbuild("increased nlink for child \"%s\" (ino #%u)\n", fd->name, fd->ino);
                 /* Can't free scan_dents so far. We might need them in pass 2 */
         }
@@ -125,7 +131,7 @@ static int jffs2_build_filesystem(struct jffs2_sb_info *c)
         dbg_fsbuild("pass 2 starting\n");
 
         for_each_inode(i, c, ic) {
-                if (ic->nlink)
+                if (ic->pino_nlink)
                         continue;
 
                 jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
@@ -232,16 +238,19 @@ static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *c,
                         /* Reduce nlink of the child. If it's now zero, stick it on the
                            dead_fds list to be cleaned up later. Else just free the fd */
 
-                        child_ic->nlink--;
+                        if (fd->type == DT_DIR)
+                                child_ic->pino_nlink = 0;
+                        else
+                                child_ic->pino_nlink--;
 
-                        if (!child_ic->nlink) {
-                                dbg_fsbuild("inode #%u (\"%s\") has now got zero nlink, adding to dead_fds list.\n",
+                        if (!child_ic->pino_nlink) {
+                                dbg_fsbuild("inode #%u (\"%s\") now has no links; adding to dead_fds list.\n",
                                           fd->ino, fd->name);
                                 fd->next = *dead_fds;
                                 *dead_fds = fd;
                         } else {
                                 dbg_fsbuild("inode #%u (\"%s\") has now got nlink %d. Ignoring.\n",
-                                          fd->ino, fd->name, child_ic->nlink);
+                                          fd->ino, fd->name, child_ic->pino_nlink);
                                 jffs2_free_full_dirent(fd);
                         }
                 }
diff --git a/fs/jffs2/dir.c b/fs/jffs2/dir.c
index 2bba3d3435b..c0c141f6fde 100644
--- a/fs/jffs2/dir.c
+++ b/fs/jffs2/dir.c
@@ -226,7 +226,8 @@ static int jffs2_create(struct inode *dir_i, struct dentry *dentry, int mode,
         d_instantiate(dentry, inode);
 
         D1(printk(KERN_DEBUG "jffs2_create: Created ino #%lu with mode %o, nlink %d(%d). nrpages %ld\n",
-                  inode->i_ino, inode->i_mode, inode->i_nlink, f->inocache->nlink, inode->i_mapping->nrpages));
+                  inode->i_ino, inode->i_mode, inode->i_nlink,
+                  f->inocache->pino_nlink, inode->i_mapping->nrpages));
         return 0;
 
  fail:
@@ -250,7 +251,7 @@ static int jffs2_unlink(struct inode *dir_i, struct dentry *dentry)
         ret = jffs2_do_unlink(c, dir_f, dentry->d_name.name,
                               dentry->d_name.len, dead_f, now);
         if (dead_f->inocache)
-                dentry->d_inode->i_nlink = dead_f->inocache->nlink;
+                dentry->d_inode->i_nlink = dead_f->inocache->pino_nlink;
         if (!ret)
                 dir_i->i_mtime = dir_i->i_ctime = ITIME(now);
         return ret;
@@ -283,7 +284,7 @@ static int jffs2_link (struct dentry *old_dentry, struct inode *dir_i, struct de
 
         if (!ret) {
                 mutex_lock(&f->sem);
-                old_dentry->d_inode->i_nlink = ++f->inocache->nlink;
+                old_dentry->d_inode->i_nlink = ++f->inocache->pino_nlink;
                 mutex_unlock(&f->sem);
                 d_instantiate(dentry, old_dentry->d_inode);
                 dir_i->i_mtime = dir_i->i_ctime = ITIME(now);
@@ -500,11 +501,14 @@ static int jffs2_mkdir (struct inode *dir_i, struct dentry *dentry, int mode)
 
         inode->i_op = &jffs2_dir_inode_operations;
         inode->i_fop = &jffs2_dir_operations;
-        /* Directories get nlink 2 at start */
-        inode->i_nlink = 2;
 
         f = JFFS2_INODE_INFO(inode);
 
+        /* Directories get nlink 2 at start */
+        inode->i_nlink = 2;
+        /* but ic->pino_nlink is the parent ino# */
+        f->inocache->pino_nlink = dir_i->i_ino;
+
         ri->data_crc = cpu_to_je32(0);
         ri->node_crc = cpu_to_je32(crc32(0, ri, sizeof(*ri)-8));
 
@@ -601,17 +605,25 @@ static int jffs2_mkdir (struct inode *dir_i, struct dentry *dentry, int mode)
 
 static int jffs2_rmdir (struct inode *dir_i, struct dentry *dentry)
 {
+        struct jffs2_sb_info *c = JFFS2_SB_INFO(dir_i->i_sb);
+        struct jffs2_inode_info *dir_f = JFFS2_INODE_INFO(dir_i);
         struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode);
         struct jffs2_full_dirent *fd;
         int ret;
+        uint32_t now = get_seconds();
 
         for (fd = f->dents ; fd; fd = fd->next) {
                 if (fd->ino)
                         return -ENOTEMPTY;
         }
-        ret = jffs2_unlink(dir_i, dentry);
-        if (!ret)
+
+        ret = jffs2_do_unlink(c, dir_f, dentry->d_name.name,
+                              dentry->d_name.len, f, now);
+        if (!ret) {
+                dir_i->i_mtime = dir_i->i_ctime = ITIME(now);
+                clear_nlink(dentry->d_inode);
                 drop_nlink(dir_i);
+        }
         return ret;
 }
 
@@ -824,7 +836,10 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
                    inode which didn't exist. */
                 if (victim_f->inocache) {
                         mutex_lock(&victim_f->sem);
-                        victim_f->inocache->nlink--;
+                        if (S_ISDIR(new_dentry->d_inode->i_mode))
+                                victim_f->inocache->pino_nlink = 0;
+                        else
+                                victim_f->inocache->pino_nlink--;
                         mutex_unlock(&victim_f->sem);
                 }
         }
@@ -845,8 +860,8 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
                 struct jffs2_inode_info *f = JFFS2_INODE_INFO(old_dentry->d_inode);
                 mutex_lock(&f->sem);
                 inc_nlink(old_dentry->d_inode);
-                if (f->inocache)
-                        f->inocache->nlink++;
+                if (f->inocache && !S_ISDIR(old_dentry->d_inode->i_mode))
+                        f->inocache->pino_nlink++;
                 mutex_unlock(&f->sem);
 
                 printk(KERN_NOTICE "jffs2_rename(): Link succeeded, unlink failed (err %d). You now have a hard link\n", ret);
diff --git a/fs/jffs2/erase.c b/fs/jffs2/erase.c
index 25a640e566d..5e86f43616a 100644
--- a/fs/jffs2/erase.c
+++ b/fs/jffs2/erase.c
@@ -294,7 +294,7 @@ static inline void jffs2_remove_node_refs_from_ino_list(struct jffs2_sb_info *c,
                         break;
 #endif
                 default:
-                        if (ic->nodes == (void *)ic && ic->nlink == 0)
+                        if (ic->nodes == (void *)ic && ic->pino_nlink == 0)
                                 jffs2_del_ino_cache(c, ic);
         }
 }
diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c
index e14b185a80d..086c4383022 100644
--- a/fs/jffs2/fs.c
+++ b/fs/jffs2/fs.c
@@ -273,7 +273,7 @@ struct inode *jffs2_iget(struct super_block *sb, unsigned long ino)
         inode->i_mtime = ITIME(je32_to_cpu(latest_node.mtime));
         inode->i_ctime = ITIME(je32_to_cpu(latest_node.ctime));
 
-        inode->i_nlink = f->inocache->nlink;
+        inode->i_nlink = f->inocache->pino_nlink;
 
         inode->i_blocks = (inode->i_size + 511) >> 9;
 
@@ -286,13 +286,12 @@ struct inode *jffs2_iget(struct super_block *sb, unsigned long ino)
         case S_IFDIR:
         {
                 struct jffs2_full_dirent *fd;
+                inode->i_nlink = 2; /* parent and '.' */
 
                 for (fd=f->dents; fd; fd = fd->next) {
                         if (fd->type == DT_DIR && fd->ino)
                                 inc_nlink(inode);
                 }
-                /* and '..' */
-                inc_nlink(inode);
                 /* Root dir gets i_nlink 3 for some reason */
                 if (inode->i_ino == 1)
                         inc_nlink(inode);
diff --git a/fs/jffs2/gc.c b/fs/jffs2/gc.c
index d4db0efecea..090c556ffed 100644
--- a/fs/jffs2/gc.c
+++ b/fs/jffs2/gc.c
@@ -161,8 +161,8 @@ int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
                         continue;
                 }
 
-                if (!ic->nlink) {
-                        D1(printk(KERN_DEBUG "Skipping check of ino #%d with nlink zero\n",
+                if (!ic->pino_nlink) {
+                        D1(printk(KERN_DEBUG "Skipping check of ino #%d with nlink/pino zero\n",
                                   ic->ino));
                         spin_unlock(&c->inocache_lock);
                         jffs2_xattr_delete_inode(c, ic);
@@ -398,7 +398,7 @@ int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
            it's vaguely possible. */
 
         inum = ic->ino;
-        nlink = ic->nlink;
+        nlink = ic->pino_nlink;
         spin_unlock(&c->inocache_lock);
 
         f = jffs2_gc_fetch_inode(c, inum, !nlink);
diff --git a/fs/jffs2/nodelist.h b/fs/jffs2/nodelist.h
index 8219df6eb6d..1750445556c 100644
--- a/fs/jffs2/nodelist.h
+++ b/fs/jffs2/nodelist.h
@@ -177,7 +177,10 @@ struct jffs2_inode_cache {
 #ifdef CONFIG_JFFS2_FS_XATTR
         struct jffs2_xattr_ref *xref;
 #endif
-        int nlink;
+        uint32_t pino_nlink;    /* Directories store parent inode
+                                   here; other inodes store nlink.
+                                   Zero always means that it's
+                                   completely unlinked. */
 };
 
 /* Inode states for 'state' above. We need the 'GC' state to prevent
diff --git a/fs/jffs2/nodemgmt.c b/fs/jffs2/nodemgmt.c
index 9df8f3ef20d..a9bf9603c1b 100644
--- a/fs/jffs2/nodemgmt.c
+++ b/fs/jffs2/nodemgmt.c
@@ -709,7 +709,7 @@ void jffs2_mark_node_obsolete(struct jffs2_sb_info *c, struct jffs2_raw_node_ref
                                 break;
 #endif
                         default:
-                                if (ic->nodes == (void *)ic && ic->nlink == 0)
+                                if (ic->nodes == (void *)ic && ic->pino_nlink == 0)
                                         jffs2_del_ino_cache(c, ic);
                                 break;
                 }
diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c
index 4cb4d76de07..9fc4833c117 100644
--- a/fs/jffs2/readinode.c
+++ b/fs/jffs2/readinode.c
@@ -1123,7 +1123,8 @@ static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c,
         size_t retlen;
         int ret;
 
-        dbg_readinode("ino #%u nlink is %d\n", f->inocache->ino, f->inocache->nlink);
+        dbg_readinode("ino #%u pino/nlink is %d\n", f->inocache->ino,
+                      f->inocache->pino_nlink);
 
         memset(&rii, 0, sizeof(rii));
 
@@ -1358,7 +1359,7 @@ int jffs2_do_read_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
                 }
                 dbg_readinode("creating inocache for root inode\n");
                 memset(f->inocache, 0, sizeof(struct jffs2_inode_cache));
-                f->inocache->ino = f->inocache->nlink = 1;
+                f->inocache->ino = f->inocache->pino_nlink = 1;
                 f->inocache->nodes = (struct jffs2_raw_node_ref *)f->inocache;
                 f->inocache->state = INO_STATE_READING;
                 jffs2_add_ino_cache(c, f->inocache);
@@ -1401,7 +1402,7 @@ void jffs2_do_clear_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
         jffs2_clear_acl(f);
         jffs2_xattr_delete_inode(c, f->inocache);
         mutex_lock(&f->sem);
-        deleted = f->inocache && !f->inocache->nlink;
+        deleted = f->inocache && !f->inocache->pino_nlink;
 
         if (f->inocache && f->inocache->state != INO_STATE_CHECKING)
                 jffs2_set_inocache_state(c, f->inocache, INO_STATE_CLEARING);
diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index 272872d27fd..8c1e692bef7 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -940,7 +940,7 @@ struct jffs2_inode_cache *jffs2_scan_make_ino_cache(struct jffs2_sb_info *c, uin
         ic->nodes = (void *)ic;
         jffs2_add_ino_cache(c, ic);
         if (ino == 1)
-                ic->nlink = 1;
+                ic->pino_nlink = 1;
         return ic;
 }
 
diff --git a/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c
index 92ab32a987b..0e78b00035e 100644
--- a/fs/jffs2/wbuf.c
+++ b/fs/jffs2/wbuf.c
@@ -494,7 +494,7 @@ static void jffs2_wbuf_recover(struct jffs2_sb_info *c)
                                 /* If it's an in-core inode, then we have to adjust any
                                    full_dirent or full_dnode structure to point to the
                                    new version instead of the old */
-                                f = jffs2_gc_fetch_inode(c, ic->ino, !ic->nlink);
+                                f = jffs2_gc_fetch_inode(c, ic->ino, !ic->pino_nlink);
                                 if (IS_ERR(f)) {
                                         /* Should never happen; it _must_ be present */
                                         JFFS2_ERROR("Failed to iget() ino #%u, err %ld\n",
diff --git a/fs/jffs2/write.c b/fs/jffs2/write.c
index 87891bdd791..ca29440e943 100644
--- a/fs/jffs2/write.c
+++ b/fs/jffs2/write.c
@@ -19,7 +19,8 @@
 #include "compr.h"
 
 
-int jffs2_do_new_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f, uint32_t mode, struct jffs2_raw_inode *ri)
+int jffs2_do_new_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
+                       uint32_t mode, struct jffs2_raw_inode *ri)
 {
         struct jffs2_inode_cache *ic;
 
@@ -31,7 +32,7 @@ int jffs2_do_new_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f, uint
         memset(ic, 0, sizeof(*ic));
 
         f->inocache = ic;
-        f->inocache->nlink = 1;
+        f->inocache->pino_nlink = 1; /* Will be overwritten shortly for directories */
         f->inocache->nodes = (struct jffs2_raw_node_ref *)f->inocache;
         f->inocache->state = INO_STATE_PRESENT;
 
@@ -635,9 +636,9 @@ int jffs2_do_unlink(struct jffs2_sb_info *c, struct jffs2_inode_info *dir_f,
                                         jffs2_mark_node_obsolete(c, fd->raw);
                                 jffs2_free_full_dirent(fd);
                         }
-                }
-
-                dead_f->inocache->nlink--;
+                        dead_f->inocache->pino_nlink = 0;
+                } else
+                        dead_f->inocache->pino_nlink--;
                 /* NB: Caller must set inode nlink if appropriate */
                 mutex_unlock(&dead_f->sem);
         }
diff --git a/fs/jffs2/xattr.c b/fs/jffs2/xattr.c
index e48665984cb..05531f291bf 100644
--- a/fs/jffs2/xattr.c
+++ b/fs/jffs2/xattr.c
@@ -592,7 +592,7 @@ void jffs2_xattr_delete_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache
            When an inode with XATTR is removed, those XATTRs must be removed. */
         struct jffs2_xattr_ref *ref, *_ref;
 
-        if (!ic || ic->nlink > 0)
+        if (!ic || ic->pino_nlink > 0)
                 return;
 
         down_write(&c->xattr_sem);
@@ -829,7 +829,7 @@ void jffs2_build_xattr_subsystem(struct jffs2_sb_info *c)
                            ref->xd and ref->ic are not valid yet. */
                         xd = jffs2_find_xattr_datum(c, ref->xid);
                         ic = jffs2_get_ino_cache(c, ref->ino);
-                        if (!xd || !ic || !ic->nlink) {
+                        if (!xd || !ic || !ic->pino_nlink) {
                                 dbg_xattr("xref(ino=%u, xid=%u, xseqno=%u) is orphan.\n",
                                           ref->ino, ref->xid, ref->xseqno);
                                 ref->xseqno |= XREF_DELETE_MARKER;