]> www.pilppa.org Git - linux-2.6-omap-h63xx.git/blobdiff - fs/autofs4/root.c
autofs4: use look aside list for lookups
[linux-2.6-omap-h63xx.git] / fs / autofs4 / root.c
index 53dabe8d5b8bd85015e56a71f744190b5301a600..dbb70d5a48827f0516db8a1455bea8b4a29b6cbb 100644 (file)
@@ -473,6 +473,8 @@ void autofs4_dentry_release(struct dentry *de)
 
                if (sbi) {
                        spin_lock(&sbi->lookup_lock);
+                       if (!list_empty(&inf->active))
+                               list_del(&inf->active);
                        if (!list_empty(&inf->expiring))
                                list_del(&inf->expiring);
                        spin_unlock(&sbi->lookup_lock);
@@ -497,6 +499,58 @@ static struct dentry_operations autofs4_dentry_operations = {
        .d_release      = autofs4_dentry_release,
 };
 
+static struct dentry *autofs4_lookup_active(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
+{
+       unsigned int len = name->len;
+       unsigned int hash = name->hash;
+       const unsigned char *str = name->name;
+       struct list_head *p, *head;
+
+       spin_lock(&dcache_lock);
+       spin_lock(&sbi->lookup_lock);
+       head = &sbi->active_list;
+       list_for_each(p, head) {
+               struct autofs_info *ino;
+               struct dentry *dentry;
+               struct qstr *qstr;
+
+               ino = list_entry(p, struct autofs_info, active);
+               dentry = ino->dentry;
+
+               spin_lock(&dentry->d_lock);
+
+               /* Already gone? */
+               if (atomic_read(&dentry->d_count) == 0)
+                       goto next;
+
+               qstr = &dentry->d_name;
+
+               if (dentry->d_name.hash != hash)
+                       goto next;
+               if (dentry->d_parent != parent)
+                       goto next;
+
+               if (qstr->len != len)
+                       goto next;
+               if (memcmp(qstr->name, str, len))
+                       goto next;
+
+               if (d_unhashed(dentry)) {
+                       dget(dentry);
+                       spin_unlock(&dentry->d_lock);
+                       spin_unlock(&sbi->lookup_lock);
+                       spin_unlock(&dcache_lock);
+                       return dentry;
+               }
+next:
+               spin_unlock(&dentry->d_lock);
+       }
+       spin_unlock(&sbi->lookup_lock);
+       spin_unlock(&dcache_lock);
+
+       return NULL;
+}
+
 static struct dentry *autofs4_lookup_expiring(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
 {
        unsigned int len = name->len;
@@ -553,7 +607,8 @@ next:
 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 {
        struct autofs_sb_info *sbi;
-       struct dentry *expiring;
+       struct autofs_info *ino;
+       struct dentry *expiring, *unhashed;
        int oz_mode;
 
        DPRINTK("name = %.*s",
@@ -571,12 +626,12 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
 
        expiring = autofs4_lookup_expiring(sbi, dentry->d_parent, &dentry->d_name);
        if (expiring) {
-               struct autofs_info *ino = autofs4_dentry_ino(expiring);
                /*
                 * If we are racing with expire the request might not
                 * be quite complete but the directory has been removed
                 * so it must have been successful, so just wait for it.
                 */
+               ino = autofs4_dentry_ino(expiring);
                while (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
                        DPRINTK("wait for incomplete expire %p name=%.*s",
                                expiring, expiring->d_name.len,
@@ -591,21 +646,41 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
                dput(expiring);
        }
 
-       /*
-        * Mark the dentry incomplete but don't hash it. We do this
-        * to serialize our inode creation operations (symlink and
-        * mkdir) which prevents deadlock during the callback to
-        * the daemon. Subsequent user space lookups for the same
-        * dentry are placed on the wait queue while the daemon
-        * itself is allowed passage unresticted so the create
-        * operation itself can then hash the dentry. Finally,
-        * we check for the hashed dentry and return the newly
-        * hashed dentry.
-        */
-       dentry->d_op = &autofs4_root_dentry_operations;
+       unhashed = autofs4_lookup_active(sbi, dentry->d_parent, &dentry->d_name);
+       if (unhashed)
+               dentry = unhashed;
+       else {
+               /*
+                * Mark the dentry incomplete but don't hash it. We do this
+                * to serialize our inode creation operations (symlink and
+                * mkdir) which prevents deadlock during the callback to
+                * the daemon. Subsequent user space lookups for the same
+                * dentry are placed on the wait queue while the daemon
+                * itself is allowed passage unresticted so the create
+                * operation itself can then hash the dentry. Finally,
+                * we check for the hashed dentry and return the newly
+                * hashed dentry.
+                */
+               dentry->d_op = &autofs4_root_dentry_operations;
+
+               /*
+                * And we need to ensure that the same dentry is used for
+                * all following lookup calls until it is hashed so that
+                * the dentry flags are persistent throughout the request.
+                */
+               ino = autofs4_init_ino(NULL, sbi, 0555);
+               if (!ino)
+                       return ERR_PTR(-ENOMEM);
+
+               dentry->d_fsdata = ino;
+               ino->dentry = dentry;
+
+               spin_lock(&sbi->lookup_lock);
+               list_add(&ino->active, &sbi->active_list);
+               spin_unlock(&sbi->lookup_lock);
 
-       dentry->d_fsdata = NULL;
-       d_instantiate(dentry, NULL);
+               d_instantiate(dentry, NULL);
+       }
 
        if (!oz_mode) {
                spin_lock(&dentry->d_lock);
@@ -630,12 +705,16 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
                        if (sigismember (sigset, SIGKILL) ||
                            sigismember (sigset, SIGQUIT) ||
                            sigismember (sigset, SIGINT)) {
+                           if (unhashed)
+                               dput(unhashed);
                            return ERR_PTR(-ERESTARTNOINTR);
                        }
                }
-               spin_lock(&dentry->d_lock);
-               dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
-               spin_unlock(&dentry->d_lock);
+               if (!oz_mode) {
+                       spin_lock(&dentry->d_lock);
+                       dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
+                       spin_unlock(&dentry->d_lock);
+               }
        }
 
        /*
@@ -659,9 +738,15 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
                else
                        dentry = ERR_PTR(-ENOENT);
 
+               if (unhashed)
+                       dput(unhashed);
+
                return dentry;
        }
 
+       if (unhashed)
+               return unhashed;
+
        return NULL;
 }
 
@@ -682,20 +767,30 @@ static int autofs4_dir_symlink(struct inode *dir,
                return -EACCES;
 
        ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
-       if (ino == NULL)
-               return -ENOSPC;
+       if (!ino)
+               return -ENOMEM;
 
-       ino->size = strlen(symname);
-       ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
+       spin_lock(&sbi->lookup_lock);
+       if (!list_empty(&ino->active))
+               list_del_init(&ino->active);
+       spin_unlock(&sbi->lookup_lock);
 
-       if (cp == NULL) {
-               kfree(ino);
-               return -ENOSPC;
+       cp = kmalloc(ino->size + 1, GFP_KERNEL);
+       if (!cp) {
+               if (!dentry->d_fsdata)
+                       kfree(ino);
+               return -ENOMEM;
        }
 
        strcpy(cp, symname);
 
        inode = autofs4_get_inode(dir->i_sb, ino);
+       if (!inode) {
+               kfree(cp);
+               if (!dentry->d_fsdata)
+                       kfree(ino);
+               return -ENOMEM;
+       }
        d_add(dentry, inode);
 
        if (dir == dir->i_sb->s_root->d_inode)
@@ -711,6 +806,8 @@ static int autofs4_dir_symlink(struct inode *dir,
                atomic_inc(&p_ino->count);
        ino->inode = inode;
 
+       ino->size = strlen(symname);
+       ino->u.symlink = cp;
        dir->i_mtime = CURRENT_TIME;
 
        return 0;
@@ -755,7 +852,8 @@ static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 
        spin_lock(&dcache_lock);
        spin_lock(&sbi->lookup_lock);
-       list_add(&ino->expiring, &sbi->expiring_list);
+       if (list_empty(&ino->expiring))
+               list_add(&ino->expiring, &sbi->expiring_list);
        spin_unlock(&sbi->lookup_lock);
        spin_lock(&dentry->d_lock);
        __d_drop(dentry);
@@ -783,7 +881,8 @@ static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
                return -ENOTEMPTY;
        }
        spin_lock(&sbi->lookup_lock);
-       list_add(&ino->expiring, &sbi->expiring_list);
+       if (list_empty(&ino->expiring))
+               list_add(&ino->expiring, &sbi->expiring_list);
        spin_unlock(&sbi->lookup_lock);
        spin_lock(&dentry->d_lock);
        __d_drop(dentry);
@@ -819,10 +918,20 @@ static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
                dentry, dentry->d_name.len, dentry->d_name.name);
 
        ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
-       if (ino == NULL)
-               return -ENOSPC;
+       if (!ino)
+               return -ENOMEM;
+
+       spin_lock(&sbi->lookup_lock);
+       if (!list_empty(&ino->active))
+               list_del_init(&ino->active);
+       spin_unlock(&sbi->lookup_lock);
 
        inode = autofs4_get_inode(dir->i_sb, ino);
+       if (!inode) {
+               if (!dentry->d_fsdata)
+                       kfree(ino);
+               return -ENOMEM;
+       }
        d_add(dentry, inode);
 
        if (dir == dir->i_sb->s_root->d_inode)