From ab90911ff90cdab59b31c045c3f0ae480d14f29d Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 14 Jan 2011 18:46:51 +0000 Subject: Allow d_manage() to be used in RCU-walk mode Allow d_manage() to be called from pathwalk when it is in RCU-walk mode as well as when it is in Ref-walk mode. This permits __follow_mount_rcu() to call d_manage() directly. d_manage() needs a parameter to indicate that it is in RCU-walk mode as it isn't allowed to sleep if in that mode (but should return -ECHILD instead). autofs4_d_manage() can then be set to retain RCU-walk mode if the daemon accesses it and otherwise request dropping back to ref-walk mode. Signed-off-by: David Howells Signed-off-by: Al Viro --- fs/autofs4/root.c | 8 ++++++-- fs/namei.c | 15 ++++++++------- 2 files changed, 14 insertions(+), 9 deletions(-) (limited to 'fs') diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 9194e274f84..dbd95512808 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -36,7 +36,7 @@ static long autofs4_root_compat_ioctl(struct file *,unsigned int,unsigned long); static int autofs4_dir_open(struct inode *inode, struct file *file); static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *); static struct vfsmount *autofs4_d_automount(struct path *); -static int autofs4_d_manage(struct dentry *, bool); +static int autofs4_d_manage(struct dentry *, bool, bool); const struct file_operations autofs4_root_operations = { .open = dcache_dir_open, @@ -450,7 +450,7 @@ done: return NULL; } -int autofs4_d_manage(struct dentry *dentry, bool mounting_here) +int autofs4_d_manage(struct dentry *dentry, bool mounting_here, bool rcu_walk) { struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); @@ -464,6 +464,10 @@ int autofs4_d_manage(struct dentry *dentry, bool mounting_here) return 0; } + /* We need to sleep, so we need pathwalk to be in ref-mode */ + if (rcu_walk) + return -ECHILD; + /* Wait for pending expires */ do_expire_wait(dentry); diff --git a/fs/namei.c b/fs/namei.c index 37385201271..5c89695ae1e 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -987,7 +987,8 @@ static int follow_managed(struct path *path, unsigned flags) if (managed & DCACHE_MANAGE_TRANSIT) { BUG_ON(!path->dentry->d_op); BUG_ON(!path->dentry->d_op->d_manage); - ret = path->dentry->d_op->d_manage(path->dentry, false); + ret = path->dentry->d_op->d_manage(path->dentry, + false, false); if (ret < 0) return ret == -EISDIR ? 0 : ret; } @@ -1048,13 +1049,12 @@ int follow_down_one(struct path *path) static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, struct inode **inode, bool reverse_transit) { - unsigned abort_mask = - reverse_transit ? 0 : DCACHE_MANAGE_TRANSIT; - while (d_mountpoint(path->dentry)) { struct vfsmount *mounted; - if (path->dentry->d_flags & abort_mask) - return true; + if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) && + !reverse_transit && + path->dentry->d_op->d_manage(path->dentry, false, true) < 0) + return false; mounted = __lookup_mnt(path->mnt, path->dentry, 1); if (!mounted) break; @@ -1132,7 +1132,8 @@ int follow_down(struct path *path, bool mounting_here) if (managed & DCACHE_MANAGE_TRANSIT) { BUG_ON(!path->dentry->d_op); BUG_ON(!path->dentry->d_op->d_manage); - ret = path->dentry->d_op->d_manage(path->dentry, mounting_here); + ret = path->dentry->d_op->d_manage( + path->dentry, mounting_here, false); if (ret < 0) return ret == -EISDIR ? 0 : ret; } -- cgit v1.2.3