From b5b801779d59165c4ecf1009009109545bd1f642 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Fri, 14 Jan 2011 18:46:03 +0000 Subject: [PATCH] autofs4: Add d_manage() dentry operation This patch required a previous patch to add the ->d_automount() dentry operation. Add a function to use the newly defined ->d_manage() dentry operation for blocking during mount and expire. Whether the VFS calls the dentry operations d_automount() and d_manage() is controled by the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags. autofs uses the d_automount() operation to callback to user space to request mount operations and the d_manage() operation to block walks into mounts that are under construction or destruction. In order to prevent these functions from being called unnecessarily the DMANAGED_* flags are cleared for cases which would cause this. In the common case the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags are both set for dentrys waiting to be mounted. The DMANAGED_TRANSIT flag is cleared upon successful mount request completion and set during expire runs, both during the dentry expire check, and if selected for expire, is left set until a subsequent successful mount request completes. The exception to this is the so-called rootless multi-mount which has no actual mount at its base. In this case the DMANAGED_AUTOMOUNT flag is cleared upon successful mount request completion as well and set again after a successful expire. Signed-off-by: Ian Kent Signed-off-by: David Howells Signed-off-by: Al Viro --- fs/autofs4/autofs_i.h | 50 ++++++++++++++++++++++++++- fs/autofs4/expire.c | 51 +++++++++++++-------------- fs/autofs4/inode.c | 3 +- fs/autofs4/root.c | 95 ++++++++++++++++++++++++++++++++++++++++++++------- 4 files changed, 159 insertions(+), 40 deletions(-) diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h index 1ebfe53..f0c95e0 100644 --- a/fs/autofs4/autofs_i.h +++ b/fs/autofs4/autofs_i.h @@ -99,7 +99,6 @@ struct autofs_info { }; #define AUTOFS_INF_EXPIRING (1<<0) /* dentry is in the process of expiring */ -#define AUTOFS_INF_MOUNTPOINT (1<<1) /* mountpoint status for direct expire */ #define AUTOFS_INF_PENDING (1<<2) /* dentry pending mount */ struct autofs_wait_queue { @@ -221,6 +220,7 @@ extern const struct file_operations autofs4_root_operations; /* Operations methods */ struct vfsmount *autofs4_d_automount(struct path *); +int autofs4_d_manage(struct dentry *, bool); /* VFS automount flags management functions */ @@ -248,6 +248,54 @@ static inline void managed_dentry_clear_automount(struct dentry *dentry) spin_unlock(&dentry->d_lock); } +static inline void __managed_dentry_set_transit(struct dentry *dentry) +{ + dentry->d_flags |= DCACHE_MANAGE_TRANSIT; +} + +static inline void managed_dentry_set_transit(struct dentry *dentry) +{ + spin_lock(&dentry->d_lock); + __managed_dentry_set_transit(dentry); + spin_unlock(&dentry->d_lock); +} + +static inline void __managed_dentry_clear_transit(struct dentry *dentry) +{ + dentry->d_flags &= ~DCACHE_MANAGE_TRANSIT; +} + +static inline void managed_dentry_clear_transit(struct dentry *dentry) +{ + spin_lock(&dentry->d_lock); + __managed_dentry_clear_transit(dentry); + spin_unlock(&dentry->d_lock); +} + +static inline void __managed_dentry_set_managed(struct dentry *dentry) +{ + dentry->d_flags |= (DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT); +} + +static inline void managed_dentry_set_managed(struct dentry *dentry) +{ + spin_lock(&dentry->d_lock); + __managed_dentry_set_managed(dentry); + spin_unlock(&dentry->d_lock); +} + +static inline void __managed_dentry_clear_managed(struct dentry *dentry) +{ + dentry->d_flags &= ~(DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT); +} + +static inline void managed_dentry_clear_managed(struct dentry *dentry) +{ + spin_lock(&dentry->d_lock); + __managed_dentry_clear_managed(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 0571ec8..3ed79d7 100644 --- a/fs/autofs4/expire.c +++ b/fs/autofs4/expire.c @@ -26,10 +26,6 @@ static inline int autofs4_can_expire(struct dentry *dentry, if (ino == NULL) return 0; - /* No point expiring a pending mount */ - if (ino->flags & AUTOFS_INF_PENDING) - return 0; - if (!do_now) { /* Too young to die */ if (!timeout || time_after(ino->last_used + timeout, now)) @@ -283,6 +279,7 @@ struct dentry *autofs4_expire_direct(struct super_block *sb, unsigned long timeout; struct dentry *root = dget(sb->s_root); int do_now = how & AUTOFS_EXP_IMMEDIATE; + struct autofs_info *ino; if (!root) return NULL; @@ -291,20 +288,21 @@ struct dentry *autofs4_expire_direct(struct super_block *sb, timeout = sbi->exp_timeout; spin_lock(&sbi->fs_lock); + ino = autofs4_dentry_ino(root); + /* No point expiring a pending mount */ + if (ino->flags & AUTOFS_INF_PENDING) { + spin_unlock(&sbi->fs_lock); + return NULL; + } + managed_dentry_set_transit(root); if (!autofs4_direct_busy(mnt, root, timeout, do_now)) { struct autofs_info *ino = autofs4_dentry_ino(root); - if (d_mountpoint(root)) { - ino->flags |= AUTOFS_INF_MOUNTPOINT; - spin_lock(&root->d_lock); - root->d_flags &= ~DCACHE_MOUNTED; - 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; } + managed_dentry_clear_transit(root); spin_unlock(&sbi->fs_lock); dput(root); @@ -341,6 +339,10 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb, while ((dentry = get_next_positive_dentry(dentry, root))) { spin_lock(&sbi->fs_lock); ino = autofs4_dentry_ino(dentry); + /* No point expiring a pending mount */ + if (ino->flags & AUTOFS_INF_PENDING) + goto cont; + managed_dentry_set_transit(dentry); /* * Case 1: (i) indirect mount or top level pseudo direct mount @@ -400,6 +402,8 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb, } } next: + managed_dentry_clear_transit(dentry); +cont: spin_unlock(&sbi->fs_lock); } return NULL; @@ -409,7 +413,6 @@ 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); @@ -482,7 +485,7 @@ int autofs4_expire_run(struct super_block *sb, ino = autofs4_dentry_ino(dentry); ino->flags &= ~AUTOFS_INF_EXPIRING; if (!d_unhashed(dentry)) - managed_dentry_clear_automount(dentry); + managed_dentry_clear_transit(dentry); complete_all(&ino->expire_complete); spin_unlock(&sbi->fs_lock); @@ -508,20 +511,18 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt, ret = autofs4_wait(sbi, dentry, NFY_EXPIRE); spin_lock(&sbi->fs_lock); - if (ino->flags & AUTOFS_INF_MOUNTPOINT) { - spin_lock(&sb->s_root->d_lock); - /* - * If we haven't been expired away, then reset - * mounted status. - */ - if (mnt->mnt_parent != mnt) - sb->s_root->d_flags |= DCACHE_MOUNTED; - spin_unlock(&sb->s_root->d_lock); - ino->flags &= ~AUTOFS_INF_MOUNTPOINT; - } ino->flags &= ~AUTOFS_INF_EXPIRING; + spin_lock(&dentry->d_lock); if (ret) - managed_dentry_clear_automount(dentry); + __managed_dentry_clear_transit(dentry); + else { + if ((IS_ROOT(dentry) || + (autofs_type_indirect(sbi->type) && + IS_ROOT(dentry->d_parent))) && + !(dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) + __managed_dentry_set_automount(dentry); + } + spin_unlock(&dentry->d_lock); 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 d0aa38c..75c1ed8 100644 --- a/fs/autofs4/inode.c +++ b/fs/autofs4/inode.c @@ -253,6 +253,7 @@ 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_manage = autofs4_d_manage, .d_release = autofs4_dentry_release, }; @@ -322,7 +323,7 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent) } if (autofs_type_trigger(sbi->type)) - __managed_dentry_set_automount(root); + __managed_dentry_set_managed(root); root_inode->i_fop = &autofs4_root_operations; root_inode->i_op = autofs_type_trigger(sbi->type) ? diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 27dc53e..f1076b9 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -424,6 +424,7 @@ static const struct dentry_operations autofs4_root_dentry_operations = { /* For other dentries */ static const struct dentry_operations autofs4_dentry_operations = { .d_automount = autofs4_d_automount, + .d_manage = autofs4_d_manage, .d_release = autofs4_dentry_release, }; @@ -604,6 +605,18 @@ struct vfsmount *autofs4_d_automount(struct path *path) DPRINTK("dentry=%p %.*s", dentry, dentry->d_name.len, dentry->d_name.name); + /* + * Someone may have manually umounted this or it was a submount + * that has gone away. + */ + spin_lock(&dentry->d_lock); + if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) { + if (!(dentry->d_flags & DCACHE_MANAGE_TRANSIT) && + (dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) + __managed_dentry_set_transit(path->dentry); + } + spin_unlock(&dentry->d_lock); + /* The daemon never triggers a mount. */ if (autofs4_oz_mode(sbi)) return NULL; @@ -633,31 +646,63 @@ struct vfsmount *autofs4_d_automount(struct path *path) /* * If the dentry is a symlink it's equivalent to a directory - * having d_mounted() true, so there's no need to call back + * having d_mountpoint() 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)) { + if (!d_mountpoint(dentry)) { + /* + * It's possible that user space hasn't removed directories + * after umounting a rootless multi-mount, although it + * should. For v5 have_submounts() is sufficient to handle + * this because the leaves of the directory tree under the + * mount never trigger mounts themselves (they have an autofs + * trigger mount mounted on them). But v4 pseudo direct mounts + * do need the leaves to to trigger mounts. In this case we + * have no choice but to use the list_empty() check and + * require user space behave. + */ + if (sbi->version > 4) { + if (have_submounts(dentry)) + goto done; + } else { + spin_lock(&dentry->d_lock); + if (!list_empty(&dentry->d_subdirs)) { + spin_unlock(&dentry->d_lock); + goto done; + } + spin_unlock(&dentry->d_lock); + } 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); + if (!(ino->flags & AUTOFS_INF_EXPIRING)) { + /* + * 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() and ->d_manage(). + */ + spin_lock(&dentry->d_lock); + __managed_dentry_clear_transit(dentry); + /* + * Only clear DMANAGED_AUTOMOUNT for rootless multi-mounts and + * symlinks as in all other cases the dentry will be covered by + * an actual mount so ->d_automount() won't be called during + * the follow. + */ + if ((!d_mountpoint(dentry) && + !list_empty(&dentry->d_subdirs)) || + (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode))) + __managed_dentry_clear_automount(dentry); + spin_unlock(&dentry->d_lock); + } spin_unlock(&sbi->fs_lock); /* Mount succeeded, check if we ended up with a new dentry */ @@ -668,6 +713,30 @@ done: return NULL; } +int autofs4_d_manage(struct dentry *dentry, bool mounting_here) +{ + struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); + + DPRINTK("dentry=%p %.*s", + dentry, dentry->d_name.len, dentry->d_name.name); + + /* The daemon never waits. */ + if (autofs4_oz_mode(sbi) || mounting_here) { + if (!d_mountpoint(dentry)) + return -EISDIR; + return 0; + } + + /* Wait for pending expires */ + do_expire_wait(dentry); + + /* + * This dentry may be under construction so wait on mount + * completion. + */ + return autofs4_mount_wait(dentry); +} + /* Lookups in the root directory */ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) { @@ -704,7 +773,7 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s /* 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); + __managed_dentry_set_managed(dentry); } ino = autofs4_init_ino(NULL, sbi, 0555); -- 2.7.4