Revert "autofs4: always use lookup for lookup"
This reverts commit 213614d583748d00967a91cacd656f417efb36ce.
Alas, ->d_revalidate() can't rely on ->lookup() finishing what
it's started; if d_alloc() in do_lookup() fails, we are not going
to call ->lookup() at all.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 30cc9dd..a015b49 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -104,99 +104,6 @@
return;
}
-static void autofs4_add_rehash_entry(struct autofs_info *ino,
- struct rehash_entry *entry)
-{
- entry->task = current;
- INIT_LIST_HEAD(&entry->list);
- list_add(&entry->list, &ino->rehash_list);
- return;
-}
-
-static void autofs4_remove_rehash_entry(struct autofs_info *ino)
-{
- struct list_head *head = &ino->rehash_list;
- struct rehash_entry *entry;
- list_for_each_entry(entry, head, list) {
- if (entry->task == current) {
- list_del(&entry->list);
- kfree(entry);
- break;
- }
- }
- return;
-}
-
-static void autofs4_remove_rehash_entrys(struct autofs_info *ino)
-{
- struct autofs_sb_info *sbi = ino->sbi;
- struct rehash_entry *entry, *next;
- struct list_head *head;
-
- spin_lock(&sbi->fs_lock);
- spin_lock(&sbi->lookup_lock);
- if (!(ino->flags & AUTOFS_INF_REHASH)) {
- spin_unlock(&sbi->lookup_lock);
- spin_unlock(&sbi->fs_lock);
- return;
- }
- ino->flags &= ~AUTOFS_INF_REHASH;
- head = &ino->rehash_list;
- list_for_each_entry_safe(entry, next, head, list) {
- list_del(&entry->list);
- kfree(entry);
- }
- spin_unlock(&sbi->lookup_lock);
- spin_unlock(&sbi->fs_lock);
- dput(ino->dentry);
-
- return;
-}
-
-static void autofs4_revalidate_drop(struct dentry *dentry,
- struct rehash_entry *entry)
-{
- struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
- struct autofs_info *ino = autofs4_dentry_ino(dentry);
- /*
- * Add to the active list so we can pick this up in
- * ->lookup(). Also add an entry to a rehash list so
- * we know when there are no dentrys in flight so we
- * know when we can rehash the dentry.
- */
- spin_lock(&sbi->lookup_lock);
- if (list_empty(&ino->active))
- list_add(&ino->active, &sbi->active_list);
- autofs4_add_rehash_entry(ino, entry);
- spin_unlock(&sbi->lookup_lock);
- if (!(ino->flags & AUTOFS_INF_REHASH)) {
- ino->flags |= AUTOFS_INF_REHASH;
- dget(dentry);
- spin_lock(&dentry->d_lock);
- __d_drop(dentry);
- spin_unlock(&dentry->d_lock);
- }
- return;
-}
-
-static void autofs4_revalidate_rehash(struct dentry *dentry)
-{
- struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
- struct autofs_info *ino = autofs4_dentry_ino(dentry);
- if (ino->flags & AUTOFS_INF_REHASH) {
- spin_lock(&sbi->lookup_lock);
- autofs4_remove_rehash_entry(ino);
- if (list_empty(&ino->rehash_list)) {
- spin_unlock(&sbi->lookup_lock);
- ino->flags &= ~AUTOFS_INF_REHASH;
- d_rehash(dentry);
- dput(ino->dentry);
- } else
- spin_unlock(&sbi->lookup_lock);
- }
- return;
-}
-
static unsigned int autofs4_need_mount(unsigned int flags)
{
unsigned int res = 0;
@@ -236,7 +143,7 @@
return dcache_dir_open(inode, file);
}
-static int try_to_fill_dentry(struct dentry *dentry)
+static int try_to_fill_dentry(struct dentry *dentry, int flags)
{
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
@@ -249,17 +156,55 @@
* Wait for a pending mount, triggering one if there
* isn't one already
*/
- DPRINTK("waiting for mount name=%.*s",
- dentry->d_name.len, dentry->d_name.name);
+ if (dentry->d_inode == NULL) {
+ DPRINTK("waiting for mount name=%.*s",
+ dentry->d_name.len, dentry->d_name.name);
- status = autofs4_wait(sbi, dentry, NFY_MOUNT);
+ status = autofs4_wait(sbi, dentry, NFY_MOUNT);
- DPRINTK("mount done status=%d", status);
+ DPRINTK("mount done status=%d", status);
- /* Update expiry counter */
- ino->last_used = jiffies;
+ /* Turn this into a real negative dentry? */
+ if (status == -ENOENT) {
+ spin_lock(&sbi->fs_lock);
+ ino->flags &= ~AUTOFS_INF_PENDING;
+ spin_unlock(&sbi->fs_lock);
+ return status;
+ } else if (status) {
+ /* Return a negative dentry, but leave it "pending" */
+ return status;
+ }
+ /* Trigger mount for path component or follow link */
+ } else if (ino->flags & AUTOFS_INF_PENDING ||
+ autofs4_need_mount(flags) ||
+ current->link_count) {
+ DPRINTK("waiting for mount name=%.*s",
+ dentry->d_name.len, dentry->d_name.name);
- return status;
+ spin_lock(&sbi->fs_lock);
+ ino->flags |= AUTOFS_INF_PENDING;
+ spin_unlock(&sbi->fs_lock);
+ status = autofs4_wait(sbi, dentry, NFY_MOUNT);
+
+ DPRINTK("mount done status=%d", status);
+
+ if (status) {
+ spin_lock(&sbi->fs_lock);
+ ino->flags &= ~AUTOFS_INF_PENDING;
+ spin_unlock(&sbi->fs_lock);
+ return status;
+ }
+ }
+
+ /* Initialize expiry counter after successful mount */
+ if (ino)
+ ino->last_used = jiffies;
+
+ spin_lock(&sbi->fs_lock);
+ ino->flags &= ~AUTOFS_INF_PENDING;
+ spin_unlock(&sbi->fs_lock);
+
+ return 0;
}
/* For autofs direct mounts the follow link triggers the mount */
@@ -313,16 +258,10 @@
*/
if (ino->flags & AUTOFS_INF_PENDING ||
(!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs))) {
- ino->flags |= AUTOFS_INF_PENDING;
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
- status = try_to_fill_dentry(dentry);
-
- spin_lock(&sbi->fs_lock);
- ino->flags &= ~AUTOFS_INF_PENDING;
- spin_unlock(&sbi->fs_lock);
-
+ status = try_to_fill_dentry(dentry, 0);
if (status)
goto out_error;
@@ -361,47 +300,18 @@
{
struct inode *dir = dentry->d_parent->d_inode;
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
- struct autofs_info *ino = autofs4_dentry_ino(dentry);
- struct rehash_entry *entry;
+ int oz_mode = autofs4_oz_mode(sbi);
int flags = nd ? nd->flags : 0;
- unsigned int mutex_aquired;
+ int status = 1;
- DPRINTK("name = %.*s oz_mode = %d",
- dentry->d_name.len, dentry->d_name.name, oz_mode);
-
- /* Daemon never causes a mount to trigger */
- if (autofs4_oz_mode(sbi))
- return 1;
-
- entry = kmalloc(sizeof(struct rehash_entry), GFP_KERNEL);
- if (!entry)
- return -ENOMEM;
-
- mutex_aquired = mutex_trylock(&dir->i_mutex);
-
- spin_lock(&sbi->fs_lock);
- spin_lock(&dcache_lock);
/* Pending dentry */
+ spin_lock(&sbi->fs_lock);
if (autofs4_ispending(dentry)) {
- int status;
-
- /*
- * We can only unhash and send this to ->lookup() if
- * the directory mutex is held over d_revalidate() and
- * ->lookup(). This prevents the VFS from incorrectly
- * seeing the dentry as non-existent.
- */
- ino->flags |= AUTOFS_INF_PENDING;
- if (!mutex_aquired) {
- autofs4_revalidate_drop(dentry, entry);
- spin_unlock(&dcache_lock);
- spin_unlock(&sbi->fs_lock);
- return 0;
- }
- spin_unlock(&dcache_lock);
+ /* The daemon never causes a mount to trigger */
spin_unlock(&sbi->fs_lock);
- mutex_unlock(&dir->i_mutex);
- kfree(entry);
+
+ if (oz_mode)
+ return 1;
/*
* If the directory has gone away due to an expire
@@ -415,82 +325,45 @@
* A zero status is success otherwise we have a
* negative error code.
*/
- status = try_to_fill_dentry(dentry);
-
- spin_lock(&sbi->fs_lock);
- ino->flags &= ~AUTOFS_INF_PENDING;
- spin_unlock(&sbi->fs_lock);
-
+ status = try_to_fill_dentry(dentry, flags);
if (status == 0)
return 1;
return status;
}
+ spin_unlock(&sbi->fs_lock);
+
+ /* Negative dentry.. invalidate if "old" */
+ if (dentry->d_inode == NULL)
+ return 0;
/* Check for a non-mountpoint directory with no contents */
+ spin_lock(&dcache_lock);
if (S_ISDIR(dentry->d_inode->i_mode) &&
!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
DPRINTK("dentry=%p %.*s, emptydir",
dentry, dentry->d_name.len, dentry->d_name.name);
+ spin_unlock(&dcache_lock);
- if (autofs4_need_mount(flags) || current->link_count) {
- int status;
+ /* The daemon never causes a mount to trigger */
+ if (oz_mode)
+ return 1;
- /*
- * We can only unhash and send this to ->lookup() if
- * the directory mutex is held over d_revalidate() and
- * ->lookup(). This prevents the VFS from incorrectly
- * seeing the dentry as non-existent.
- */
- ino->flags |= AUTOFS_INF_PENDING;
- if (!mutex_aquired) {
- autofs4_revalidate_drop(dentry, entry);
- spin_unlock(&dcache_lock);
- spin_unlock(&sbi->fs_lock);
- return 0;
- }
- spin_unlock(&dcache_lock);
- spin_unlock(&sbi->fs_lock);
- mutex_unlock(&dir->i_mutex);
- kfree(entry);
+ /*
+ * A zero status is success otherwise we have a
+ * negative error code.
+ */
+ status = try_to_fill_dentry(dentry, flags);
+ if (status == 0)
+ return 1;
- /*
- * A zero status is success otherwise we have a
- * negative error code.
- */
- status = try_to_fill_dentry(dentry);
-
- spin_lock(&sbi->fs_lock);
- ino->flags &= ~AUTOFS_INF_PENDING;
- spin_unlock(&sbi->fs_lock);
-
- if (status == 0)
- return 1;
-
- return status;
- }
+ return status;
}
spin_unlock(&dcache_lock);
- spin_unlock(&sbi->fs_lock);
-
- if (mutex_aquired)
- mutex_unlock(&dir->i_mutex);
-
- kfree(entry);
return 1;
}
-static void autofs4_free_rehash_entrys(struct autofs_info *inf)
-{
- struct list_head *head = &inf->rehash_list;
- struct rehash_entry *entry, *next;
- list_for_each_entry_safe(entry, next, head, list) {
- list_del(&entry->list);
- kfree(entry);
- }
-}
-
void autofs4_dentry_release(struct dentry *de)
{
struct autofs_info *inf;
@@ -509,8 +382,6 @@
list_del(&inf->active);
if (!list_empty(&inf->expiring))
list_del(&inf->expiring);
- if (!list_empty(&inf->rehash_list))
- autofs4_free_rehash_entrys(inf);
spin_unlock(&sbi->lookup_lock);
}
@@ -543,7 +414,6 @@
const unsigned char *str = name->name;
struct list_head *p, *head;
-restart:
spin_lock(&dcache_lock);
spin_lock(&sbi->lookup_lock);
head = &sbi->active_list;
@@ -561,19 +431,6 @@
if (atomic_read(&active->d_count) == 0)
goto next;
- if (active->d_inode && IS_DEADDIR(active->d_inode)) {
- if (!list_empty(&ino->rehash_list)) {
- dget(active);
- spin_unlock(&active->d_lock);
- spin_unlock(&sbi->lookup_lock);
- spin_unlock(&dcache_lock);
- autofs4_remove_rehash_entrys(ino);
- dput(active);
- goto restart;
- }
- goto next;
- }
-
qstr = &active->d_name;
if (active->d_name.hash != hash)
@@ -586,11 +443,13 @@
if (memcmp(qstr->name, str, len))
goto next;
- dget(active);
- spin_unlock(&active->d_lock);
- spin_unlock(&sbi->lookup_lock);
- spin_unlock(&dcache_lock);
- return active;
+ if (d_unhashed(active)) {
+ dget(active);
+ spin_unlock(&active->d_lock);
+ spin_unlock(&sbi->lookup_lock);
+ spin_unlock(&dcache_lock);
+ return active;
+ }
next:
spin_unlock(&active->d_lock);
}
@@ -639,11 +498,13 @@
if (memcmp(qstr->name, str, len))
goto next;
- dget(expiring);
- spin_unlock(&expiring->d_lock);
- spin_unlock(&sbi->lookup_lock);
- spin_unlock(&dcache_lock);
- return expiring;
+ if (d_unhashed(expiring)) {
+ dget(expiring);
+ spin_unlock(&expiring->d_lock);
+ spin_unlock(&sbi->lookup_lock);
+ spin_unlock(&dcache_lock);
+ return expiring;
+ }
next:
spin_unlock(&expiring->d_lock);
}
@@ -653,48 +514,6 @@
return NULL;
}
-static struct autofs_info *init_new_dentry(struct autofs_sb_info *sbi,
- struct dentry *dentry, int oz_mode)
-{
- struct autofs_info *ino;
-
- /*
- * 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;
-
- /*
- * Only set the mount pending flag for new dentrys not created
- * by the daemon.
- */
- if (!oz_mode)
- ino->flags |= AUTOFS_INF_PENDING;
-
- d_instantiate(dentry, NULL);
-
- return ino;
-}
-
/* Lookups in the root directory */
static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
@@ -702,7 +521,6 @@
struct autofs_info *ino;
struct dentry *expiring, *active;
int oz_mode;
- int status = 0;
DPRINTK("name = %.*s",
dentry->d_name.len, dentry->d_name.name);
@@ -717,26 +535,44 @@
DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
- spin_lock(&sbi->fs_lock);
active = autofs4_lookup_active(dentry);
if (active) {
dentry = active;
ino = autofs4_dentry_ino(dentry);
- /* If this came from revalidate, rehash it */
- autofs4_revalidate_rehash(dentry);
- spin_unlock(&sbi->fs_lock);
} else {
- spin_unlock(&sbi->fs_lock);
- ino = init_new_dentry(sbi, dentry, oz_mode);
- if (IS_ERR(ino))
- return (struct dentry *) ino;
+ /*
+ * 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;
+
+ autofs4_add_active(dentry);
+
+ d_instantiate(dentry, NULL);
}
- autofs4_add_active(dentry);
-
if (!oz_mode) {
- expiring = autofs4_lookup_expiring(dentry);
mutex_unlock(&dir->i_mutex);
+ expiring = autofs4_lookup_expiring(dentry);
if (expiring) {
/*
* If we are racing with expire the request might not
@@ -744,22 +580,23 @@
* so it must have been successful, so just wait for it.
*/
autofs4_expire_wait(expiring);
+ autofs4_del_expiring(expiring);
dput(expiring);
}
- status = try_to_fill_dentry(dentry);
- mutex_lock(&dir->i_mutex);
+
spin_lock(&sbi->fs_lock);
- ino->flags &= ~AUTOFS_INF_PENDING;
+ ino->flags |= AUTOFS_INF_PENDING;
spin_unlock(&sbi->fs_lock);
+ if (dentry->d_op && dentry->d_op->d_revalidate)
+ (dentry->d_op->d_revalidate)(dentry, nd);
+ mutex_lock(&dir->i_mutex);
}
- autofs4_del_active(dentry);
-
/*
- * If we had a mount fail, check if we had to handle
+ * If we are still pending, check if we had to handle
* a signal. If so we can force a restart..
*/
- if (status) {
+ if (ino->flags & AUTOFS_INF_PENDING) {
/* See if we were interrupted */
if (signal_pending(current)) {
sigset_t *sigset = ¤t->pending.signal;
@@ -771,46 +608,43 @@
return ERR_PTR(-ERESTARTNOINTR);
}
}
- }
-
- /*
- * User space can (and has done in the past) remove and re-create
- * this directory during the callback. This can leave us with an
- * unhashed dentry, but a successful mount! So we need to
- * perform another cached lookup in case the dentry now exists.
- */
- if (!oz_mode && !have_submounts(dentry)) {
- struct dentry *new;
- new = d_lookup(dentry->d_parent, &dentry->d_name);
- if (new) {
- if (active)
- dput(active);
- return new;
- } else {
- if (!status)
- status = -ENOENT;
+ if (!oz_mode) {
+ spin_lock(&sbi->fs_lock);
+ ino->flags &= ~AUTOFS_INF_PENDING;
+ spin_unlock(&sbi->fs_lock);
}
}
/*
- * If we had a mount failure, return status to user space.
- * If the mount succeeded and we used a dentry from the active queue
- * return it.
+ * If this dentry is unhashed, then we shouldn't honour this
+ * lookup. Returning ENOENT here doesn't do the right thing
+ * for all system calls, but it should be OK for the operations
+ * we permit from an autofs.
*/
- if (status) {
- dentry = ERR_PTR(status);
+ if (!oz_mode && d_unhashed(dentry)) {
+ /*
+ * A user space application can (and has done in the past)
+ * remove and re-create this directory during the callback.
+ * This can leave us with an unhashed dentry, but a
+ * successful mount! So we need to perform another
+ * cached lookup in case the dentry now exists.
+ */
+ struct dentry *parent = dentry->d_parent;
+ struct dentry *new = d_lookup(parent, &dentry->d_name);
+ if (new != NULL)
+ dentry = new;
+ else
+ dentry = ERR_PTR(-ENOENT);
+
if (active)
dput(active);
+
return dentry;
- } else {
- /*
- * Valid successful mount, return active dentry or NULL
- * for a new dentry.
- */
- if (active)
- return active;
}
+ if (active)
+ return active;
+
return NULL;
}
@@ -834,6 +668,8 @@
if (!ino)
return -ENOMEM;
+ autofs4_del_active(dentry);
+
ino->size = strlen(symname);
cp = kmalloc(ino->size + 1, GFP_KERNEL);
if (!cp) {
@@ -910,6 +746,7 @@
dir->i_mtime = CURRENT_TIME;
spin_lock(&dcache_lock);
+ autofs4_add_expiring(dentry);
spin_lock(&dentry->d_lock);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
@@ -935,6 +772,7 @@
spin_unlock(&dcache_lock);
return -ENOTEMPTY;
}
+ autofs4_add_expiring(dentry);
spin_lock(&dentry->d_lock);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
@@ -972,6 +810,8 @@
if (!ino)
return -ENOMEM;
+ autofs4_del_active(dentry);
+
inode = autofs4_get_inode(dir->i_sb, ino);
if (!inode) {
if (!dentry->d_fsdata)