From 10584211e48036182212b598cc53331776406d60 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Fri, 14 Jan 2011 18:45:58 +0000 Subject: 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 Signed-off-by: David Howells Signed-off-by: Al Viro --- fs/autofs4/autofs_i.h | 30 ++++++ fs/autofs4/expire.c | 6 ++ fs/autofs4/inode.c | 4 + fs/autofs4/root.c | 261 ++++++++++++++++++++++++++++---------------------- 4 files changed, 189 insertions(+), 112 deletions(-) (limited to 'fs') diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h index eb67953452b..1ebfe53872b 100644 --- a/fs/autofs4/autofs_i.h +++ b/fs/autofs4/autofs_i.h @@ -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); diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c index 6a930b90d38..0571ec8352b 100644 --- a/fs/autofs4/expire.c +++ b/fs/autofs4/expire.c @@ -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); diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c index a7bdb9dcac8..d0aa38cac30 100644 --- a/fs/autofs4/inode.c +++ b/fs/autofs4/inode.c @@ -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 : diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 20225636a4e..27dc53e111f 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -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 = ¤t->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); -- cgit v1.2.3-18-g5258