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autofs4: Add d_automount() dentry operation 

Add a function to use the newly defined ->d_automount() dentry operation
for triggering mounts instead of doing the user space callback in ->lookup()
and ->d_revalidate().

Note, to be useful the subsequent patch to add the ->d_manage() dentry
operation is also needed so the discussion of functionality is deferred to
that patch.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Ian Kent 2011-01-14 18:45:58 +00:00 коммит произвёл Al Viro
Родитель db3729153e
Коммит 10584211e4
4 изменённых файлов: 189 добавлений и 112 удалений
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30
fs/autofs4/autofs_i.h
Просмотреть файл

@ -218,6 +218,36 @@ extern const struct inode_operations autofs4_direct_root_inode_operations;
extern const struct file_operations autofs4_dir_operations;
extern const struct file_operations autofs4_root_operations;
/* Operations methods */
struct vfsmount *autofs4_d_automount(struct path *);
/* VFS automount flags management functions */
static inline void __managed_dentry_set_automount(struct dentry *dentry)
{
dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
}
static inline void managed_dentry_set_automount(struct dentry *dentry)
{
spin_lock(&dentry->d_lock);
__managed_dentry_set_automount(dentry);
spin_unlock(&dentry->d_lock);
}
static inline void __managed_dentry_clear_automount(struct dentry *dentry)
{
dentry->d_flags &= ~DCACHE_NEED_AUTOMOUNT;
}
static inline void managed_dentry_clear_automount(struct dentry *dentry)
{
spin_lock(&dentry->d_lock);
__managed_dentry_clear_automount(dentry);
spin_unlock(&dentry->d_lock);
}
/* Initializing function */
int autofs4_fill_super(struct super_block *, void *, int);

6
fs/autofs4/expire.c
Просмотреть файл

@ -300,6 +300,7 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
spin_unlock(&root->d_lock);
}
ino->flags |= AUTOFS_INF_EXPIRING;
managed_dentry_set_automount(root);
init_completion(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
return root;
@ -408,6 +409,7 @@ found:
expired, (int)expired->d_name.len, expired->d_name.name);
ino = autofs4_dentry_ino(expired);
ino->flags |= AUTOFS_INF_EXPIRING;
managed_dentry_set_automount(expired);
init_completion(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
spin_lock(&autofs4_lock);
@ -479,6 +481,8 @@ int autofs4_expire_run(struct super_block *sb,
spin_lock(&sbi->fs_lock);
ino = autofs4_dentry_ino(dentry);
ino->flags &= ~AUTOFS_INF_EXPIRING;
if (!d_unhashed(dentry))
managed_dentry_clear_automount(dentry);
complete_all(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
@ -516,6 +520,8 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
}
ino->flags &= ~AUTOFS_INF_EXPIRING;
if (ret)
managed_dentry_clear_automount(dentry);
complete_all(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
dput(dentry);

4
fs/autofs4/inode.c
Просмотреть файл

@ -252,6 +252,7 @@ static struct autofs_info *autofs4_mkroot(struct autofs_sb_info *sbi)
}
static const struct dentry_operations autofs4_sb_dentry_operations = {
.d_automount = autofs4_d_automount,
.d_release = autofs4_dentry_release,
};
@ -320,6 +321,9 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
goto fail_dput;
}
if (autofs_type_trigger(sbi->type))
__managed_dentry_set_automount(root);
root_inode->i_fop = &autofs4_root_operations;
root_inode->i_op = autofs_type_trigger(sbi->type) ?
&autofs4_direct_root_inode_operations :

261
fs/autofs4/root.c
Просмотреть файл

@ -35,7 +35,6 @@ static long autofs4_root_compat_ioctl(struct file *,unsigned int,unsigned long);
#endif
static int autofs4_dir_open(struct inode *inode, struct file *file);
static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
static void *autofs4_follow_link(struct dentry *, struct nameidata *);
#define TRIGGER_FLAGS (LOOKUP_CONTINUE | LOOKUP_DIRECTORY)
#define TRIGGER_INTENTS (LOOKUP_OPEN | LOOKUP_CREATE)
@ -73,7 +72,6 @@ const struct inode_operations autofs4_direct_root_inode_operations = {
.unlink = autofs4_dir_unlink,
.mkdir = autofs4_dir_mkdir,
.rmdir = autofs4_dir_rmdir,
.follow_link = autofs4_follow_link,
};
const struct inode_operations autofs4_dir_inode_operations = {
@ -420,13 +418,12 @@ void autofs4_dentry_release(struct dentry *de)
/* For dentries of directories in the root dir */
static const struct dentry_operations autofs4_root_dentry_operations = {
.d_revalidate = autofs4_revalidate,
.d_release = autofs4_dentry_release,
};
/* For other dentries */
static const struct dentry_operations autofs4_dentry_operations = {
.d_revalidate = autofs4_revalidate,
.d_automount = autofs4_d_automount,
.d_release = autofs4_dentry_release,
};
@ -540,50 +537,176 @@ next:
return NULL;
}
static int autofs4_mount_wait(struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
int status;
if (ino->flags & AUTOFS_INF_PENDING) {
DPRINTK("waiting for mount name=%.*s",
dentry->d_name.len, dentry->d_name.name);
status = autofs4_wait(sbi, dentry, NFY_MOUNT);
DPRINTK("mount wait done status=%d", status);
ino->last_used = jiffies;
return status;
}
return 0;
}
static int do_expire_wait(struct dentry *dentry)
{
struct dentry *expiring;
expiring = autofs4_lookup_expiring(dentry);
if (!expiring)
return autofs4_expire_wait(dentry);
else {
/*
* 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, just wait for it.
*/
autofs4_expire_wait(expiring);
autofs4_del_expiring(expiring);
dput(expiring);
}
return 0;
}
static struct dentry *autofs4_mountpoint_changed(struct path *path)
{
struct dentry *dentry = path->dentry;
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
/*
* If this is an indirect mount the dentry could have gone away
* as a result of an expire and a new one created.
*/
if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
struct dentry *parent = dentry->d_parent;
struct dentry *new = d_lookup(parent, &dentry->d_name);
if (!new)
return NULL;
dput(path->dentry);
path->dentry = new;
}
return path->dentry;
}
struct vfsmount *autofs4_d_automount(struct path *path)
{
struct dentry *dentry = path->dentry;
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
int status;
DPRINTK("dentry=%p %.*s",
dentry, dentry->d_name.len, dentry->d_name.name);
/* The daemon never triggers a mount. */
if (autofs4_oz_mode(sbi))
return NULL;
/*
* If an expire request is pending everyone must wait.
* If the expire fails we're still mounted so continue
* the follow and return. A return of -EAGAIN (which only
* happens with indirect mounts) means the expire completed
* and the directory was removed, so just go ahead and try
* the mount.
*/
status = do_expire_wait(dentry);
if (status && status != -EAGAIN)
return NULL;
/* Callback to the daemon to perform the mount or wait */
spin_lock(&sbi->fs_lock);
if (ino->flags & AUTOFS_INF_PENDING) {
spin_unlock(&sbi->fs_lock);
status = autofs4_mount_wait(dentry);
if (status)
return ERR_PTR(status);
spin_lock(&sbi->fs_lock);
goto done;
}
/*
* If the dentry is a symlink it's equivalent to a directory
* having d_mounted() true, so there's no need to call back
* to the daemon.
*/
if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode))
goto done;
spin_lock(&dentry->d_lock);
if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
ino->flags |= AUTOFS_INF_PENDING;
spin_unlock(&dentry->d_lock);
spin_unlock(&sbi->fs_lock);
status = autofs4_mount_wait(dentry);
if (status)
return ERR_PTR(status);
spin_lock(&sbi->fs_lock);
ino->flags &= ~AUTOFS_INF_PENDING;
goto done;
}
spin_unlock(&dentry->d_lock);
done:
/*
* Any needed mounting has been completed and the path updated
* so turn this into a normal dentry so we don't continually
* call ->d_automount().
*/
managed_dentry_clear_automount(dentry);
spin_unlock(&sbi->fs_lock);
/* Mount succeeded, check if we ended up with a new dentry */
dentry = autofs4_mountpoint_changed(path);
if (!dentry)
return ERR_PTR(-ENOENT);
return NULL;
}
/* Lookups in the root directory */
static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
struct autofs_sb_info *sbi;
struct autofs_info *ino;
struct dentry *expiring, *active;
int oz_mode;
struct dentry *active;
DPRINTK("name = %.*s",
dentry->d_name.len, dentry->d_name.name);
DPRINTK("name = %.*s", dentry->d_name.len, dentry->d_name.name);
/* File name too long to exist */
if (dentry->d_name.len > NAME_MAX)
return ERR_PTR(-ENAMETOOLONG);
sbi = autofs4_sbi(dir->i_sb);
oz_mode = autofs4_oz_mode(sbi);
DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
active = autofs4_lookup_active(dentry);
if (active) {
dentry = active;
ino = autofs4_dentry_ino(dentry);
return active;
} 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.
*/
d_set_d_op(dentry, &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.
* A dentry that is not within the root can never trigger a
* mount operation, unless the directory already exists, so we
* can return fail immediately. The daemon however does need
* to create directories within the file system.
*/
if (!autofs4_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
return ERR_PTR(-ENOENT);
/* Mark entries in the root as mount triggers */
if (autofs_type_indirect(sbi->type) && IS_ROOT(dentry->d_parent)) {
d_set_d_op(dentry, &autofs4_dentry_operations);
managed_dentry_set_automount(dentry);
}
ino = autofs4_init_ino(NULL, sbi, 0555);
if (!ino)
return ERR_PTR(-ENOMEM);
@ -595,82 +718,6 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
d_instantiate(dentry, NULL);
}
if (!oz_mode) {
mutex_unlock(&dir->i_mutex);
expiring = autofs4_lookup_expiring(dentry);
if (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.
*/
autofs4_expire_wait(expiring);
autofs4_del_expiring(expiring);
dput(expiring);
}
spin_lock(&sbi->fs_lock);
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);
}
/*
* If we are still pending, check if we had to handle
* a signal. If so we can force a restart..
*/
if (ino->flags & AUTOFS_INF_PENDING) {
/* See if we were interrupted */
if (signal_pending(current)) {
sigset_t *sigset = &current->pending.signal;
if (sigismember (sigset, SIGKILL) ||
sigismember (sigset, SIGQUIT) ||
sigismember (sigset, SIGINT)) {
if (active)
dput(active);
return ERR_PTR(-ERESTARTNOINTR);
}
}
if (!oz_mode) {
spin_lock(&sbi->fs_lock);
ino->flags &= ~AUTOFS_INF_PENDING;
spin_unlock(&sbi->fs_lock);
}
}
/*
* 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 (!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;
}
if (active)
return active;
return NULL;
}
@ -715,11 +762,6 @@ static int autofs4_dir_symlink(struct inode *dir,
}
d_add(dentry, inode);
if (dir == dir->i_sb->s_root->d_inode)
d_set_d_op(dentry, &autofs4_root_dentry_operations);
else
d_set_d_op(dentry, &autofs4_dentry_operations);
dentry->d_fsdata = ino;
ino->dentry = dget(dentry);
atomic_inc(&ino->count);
@ -850,11 +892,6 @@ static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
}
d_add(dentry, inode);
if (dir == dir->i_sb->s_root->d_inode)
d_set_d_op(dentry, &autofs4_root_dentry_operations);
else
d_set_d_op(dentry, &autofs4_dentry_operations);
dentry->d_fsdata = ino;
ino->dentry = dget(dentry);
atomic_inc(&ino->count);