From fb5f51c7425ebc808d91329257cbc963e2421368 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Thu, 24 Nov 2016 08:03:41 +1100 Subject: vfs: change d_manage() to take a struct path For the autofs module to be able to reliably check if a dentry is a mountpoint in a multiple namespace environment the ->d_manage() dentry operation will need to take a path argument instead of a dentry. Link: http://lkml.kernel.org/r/20161011053352.27645.83962.stgit@pluto.themaw.net Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- Documentation/filesystems/Locking | 2 +- Documentation/filesystems/vfs.txt | 2 +- fs/autofs4/root.c | 5 +++-- fs/namei.c | 13 ++++++------- include/linux/dcache.h | 2 +- 5 files changed, 12 insertions(+), 12 deletions(-) diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 1b5f156..4ca3a8d 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -20,7 +20,7 @@ prototypes: void (*d_iput)(struct dentry *, struct inode *); char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen); struct vfsmount *(*d_automount)(struct path *path); - int (*d_manage)(struct dentry *, bool); + int (*d_manage)(const struct path *, bool); struct dentry *(*d_real)(struct dentry *, const struct inode *, unsigned int); diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index b5039a0..3893f4d 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -948,7 +948,7 @@ struct dentry_operations { void (*d_iput)(struct dentry *, struct inode *); char *(*d_dname)(struct dentry *, char *, int); struct vfsmount *(*d_automount)(struct path *); - int (*d_manage)(struct dentry *, bool); + int (*d_manage)(const struct path *, bool); struct dentry *(*d_real)(struct dentry *, const struct inode *, unsigned int); }; diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index a11f731..3a43282 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -32,7 +32,7 @@ static int autofs4_dir_open(struct inode *inode, struct file *file); static struct dentry *autofs4_lookup(struct inode *, struct dentry *, unsigned int); static struct vfsmount *autofs4_d_automount(struct path *); -static int autofs4_d_manage(struct dentry *, bool); +static int autofs4_d_manage(const struct path *, bool); static void autofs4_dentry_release(struct dentry *); const struct file_operations autofs4_root_operations = { @@ -421,8 +421,9 @@ done: return NULL; } -static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk) +static int autofs4_d_manage(const struct path *path, bool rcu_walk) { + 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; diff --git a/fs/namei.c b/fs/namei.c index 5b4eed2..81ac473 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1200,7 +1200,7 @@ static int follow_managed(struct path *path, struct nameidata *nd) 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, false); if (ret < 0) break; } @@ -1263,10 +1263,10 @@ int follow_down_one(struct path *path) } EXPORT_SYMBOL(follow_down_one); -static inline int managed_dentry_rcu(struct dentry *dentry) +static inline int managed_dentry_rcu(const struct path *path) { - return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? - dentry->d_op->d_manage(dentry, true) : 0; + return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? + path->dentry->d_op->d_manage(path, true) : 0; } /* @@ -1282,7 +1282,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, * Don't forget we might have a non-mountpoint managed dentry * that wants to block transit. */ - switch (managed_dentry_rcu(path->dentry)) { + switch (managed_dentry_rcu(path)) { case -ECHILD: default: return false; @@ -1392,8 +1392,7 @@ int follow_down(struct path *path) 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, false); if (ret < 0) return ret == -EISDIR ? 0 : ret; } diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 5beed7b..bc529ce 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -139,7 +139,7 @@ struct dentry_operations { void (*d_iput)(struct dentry *, struct inode *); char *(*d_dname)(struct dentry *, char *, int); struct vfsmount *(*d_automount)(struct path *); - int (*d_manage)(struct dentry *, bool); + int (*d_manage)(const struct path *, bool); struct dentry *(*d_real)(struct dentry *, const struct inode *, unsigned int); } ____cacheline_aligned; -- cgit v1.1 From c6609c0a1c34fc097152b28b496236625673924f Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Thu, 24 Nov 2016 08:03:41 +1100 Subject: vfs: add path_is_mountpoint() helper d_mountpoint() can only be used reliably to establish if a dentry is not mounted in any namespace. It isn't aware of the possibility there may be multiple mounts using a given dentry that may be in a different namespace. Add helper functions, path_is_mountpoint(), that checks if a struct path is a mountpoint for this case. Link: http://lkml.kernel.org/r/20161011053358.27645.9729.stgit@pluto.themaw.net Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/mount.h | 6 ++++++ fs/namespace.c | 29 +++++++++++++++++++++++++++++ include/linux/mount.h | 2 ++ 3 files changed, 37 insertions(+) diff --git a/fs/mount.h b/fs/mount.h index d2e25d7..2c856fc 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -94,6 +94,12 @@ extern struct mount *__lookup_mnt_last(struct vfsmount *, struct dentry *); extern int __legitimize_mnt(struct vfsmount *, unsigned); extern bool legitimize_mnt(struct vfsmount *, unsigned); +static inline bool __path_is_mountpoint(const struct path *path) +{ + struct mount *m = __lookup_mnt(path->mnt, path->dentry); + return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT)); +} + extern void __detach_mounts(struct dentry *dentry); static inline void detach_mounts(struct dentry *dentry) diff --git a/fs/namespace.c b/fs/namespace.c index e6c234b..7a73383 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1159,6 +1159,35 @@ struct vfsmount *mntget(struct vfsmount *mnt) } EXPORT_SYMBOL(mntget); +/* path_is_mountpoint() - Check if path is a mount in the current + * namespace. + * + * d_mountpoint() can only be used reliably to establish if a dentry is + * not mounted in any namespace and that common case is handled inline. + * d_mountpoint() isn't aware of the possibility there may be multiple + * mounts using a given dentry in a different namespace. This function + * checks if the passed in path is a mountpoint rather than the dentry + * alone. + */ +bool path_is_mountpoint(const struct path *path) +{ + unsigned seq; + bool res; + + if (!d_mountpoint(path->dentry)) + return false; + + rcu_read_lock(); + do { + seq = read_seqbegin(&mount_lock); + res = __path_is_mountpoint(path); + } while (read_seqretry(&mount_lock, seq)); + rcu_read_unlock(); + + return res; +} +EXPORT_SYMBOL(path_is_mountpoint); + struct vfsmount *mnt_clone_internal(struct path *path) { struct mount *p; diff --git a/include/linux/mount.h b/include/linux/mount.h index 1172cce..5b6dd00 100644 --- a/include/linux/mount.h +++ b/include/linux/mount.h @@ -98,4 +98,6 @@ extern dev_t name_to_dev_t(const char *name); extern unsigned int sysctl_mount_max; +extern bool path_is_mountpoint(const struct path *path); + #endif /* _LINUX_MOUNT_H */ -- cgit v1.1 From 01619491a5f0766014fe863c5ae480665436e7a2 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Thu, 24 Nov 2016 08:03:41 +1100 Subject: vfs: add path_has_submounts() d_mountpoint() can only be used reliably to establish if a dentry is not mounted in any namespace. It isn't aware of the possibility there may be multiple mounts using the given dentry, possibly in a different namespace. Add function, path_has_submounts(), that checks is a struct path contains mounts (or is a mountpoint itself) to handle this case. Link: http://lkml.kernel.org/r/20161011053403.27645.55242.stgit@pluto.themaw.net Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/dcache.c | 39 +++++++++++++++++++++++++++++++++++++++ include/linux/dcache.h | 1 + 2 files changed, 40 insertions(+) diff --git a/fs/dcache.c b/fs/dcache.c index 5c7cc95..8515875 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1306,6 +1306,45 @@ int have_submounts(struct dentry *parent) } EXPORT_SYMBOL(have_submounts); +struct check_mount { + struct vfsmount *mnt; + unsigned int mounted; +}; + +static enum d_walk_ret path_check_mount(void *data, struct dentry *dentry) +{ + struct check_mount *info = data; + struct path path = { .mnt = info->mnt, .dentry = dentry }; + + if (likely(!d_mountpoint(dentry))) + return D_WALK_CONTINUE; + if (__path_is_mountpoint(&path)) { + info->mounted = 1; + return D_WALK_QUIT; + } + return D_WALK_CONTINUE; +} + +/** + * path_has_submounts - check for mounts over a dentry in the + * current namespace. + * @parent: path to check. + * + * Return true if the parent or its subdirectories contain + * a mount point in the current namespace. + */ +int path_has_submounts(const struct path *parent) +{ + struct check_mount data = { .mnt = parent->mnt, .mounted = 0 }; + + read_seqlock_excl(&mount_lock); + d_walk(parent->dentry, &data, path_check_mount, NULL); + read_sequnlock_excl(&mount_lock); + + return data.mounted; +} +EXPORT_SYMBOL(path_has_submounts); + /* * Called by mount code to set a mountpoint and check if the mountpoint is * reachable (e.g. NFS can unhash a directory dentry and then the complete diff --git a/include/linux/dcache.h b/include/linux/dcache.h index bc529ce..0ffaf7a 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -255,6 +255,7 @@ extern void d_prune_aliases(struct inode *); /* test whether we have any submounts in a subdir tree */ extern int have_submounts(struct dentry *); +extern int path_has_submounts(const struct path *); /* * This adds the entry to the hash queues. -- cgit v1.1 From 74f504cff50b918f8ec2762b1513ae755da56a95 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Thu, 24 Nov 2016 08:03:41 +1100 Subject: autofs: change autofs4_expire_wait()/do_expire_wait() to take struct path In order to use the functions path_is_mountpoint() and path_has_submounts() autofs needs to pass a struct path in several places. Start by changing autofs4_expire_wait() and do_expire_wait() to take a struct path instead of a struct dentry. Link: http://lkml.kernel.org/r/20161011053408.27645.40091.stgit@pluto.themaw.net Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/autofs4/autofs_i.h | 2 +- fs/autofs4/dev-ioctl.c | 2 +- fs/autofs4/expire.c | 3 ++- fs/autofs4/root.c | 12 +++++++----- 4 files changed, 11 insertions(+), 8 deletions(-) diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h index a1fba42..4531152 100644 --- a/fs/autofs4/autofs_i.h +++ b/fs/autofs4/autofs_i.h @@ -145,7 +145,7 @@ void autofs4_free_ino(struct autofs_info *); /* Expiration */ int is_autofs4_dentry(struct dentry *); -int autofs4_expire_wait(struct dentry *dentry, int rcu_walk); +int autofs4_expire_wait(const struct path *path, int rcu_walk); int autofs4_expire_run(struct super_block *, struct vfsmount *, struct autofs_sb_info *, struct autofs_packet_expire __user *); diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c index fc09eb7..40c69f9 100644 --- a/fs/autofs4/dev-ioctl.c +++ b/fs/autofs4/dev-ioctl.c @@ -468,7 +468,7 @@ static int autofs_dev_ioctl_requester(struct file *fp, ino = autofs4_dentry_ino(path.dentry); if (ino) { err = 0; - autofs4_expire_wait(path.dentry, 0); + autofs4_expire_wait(&path, 0); spin_lock(&sbi->fs_lock); param->requester.uid = from_kuid_munged(current_user_ns(), ino->uid); diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c index d8e6d42..6ba6107 100644 --- a/fs/autofs4/expire.c +++ b/fs/autofs4/expire.c @@ -495,8 +495,9 @@ found: return expired; } -int autofs4_expire_wait(struct dentry *dentry, int rcu_walk) +int autofs4_expire_wait(const struct path *path, int rcu_walk) { + 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; diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 3a43282..6b06337 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -286,22 +286,24 @@ static int autofs4_mount_wait(struct dentry *dentry, bool rcu_walk) return status; } -static int do_expire_wait(struct dentry *dentry, bool rcu_walk) +static int do_expire_wait(const struct path *path, bool rcu_walk) { + struct dentry *dentry = path->dentry; struct dentry *expiring; expiring = autofs4_lookup_expiring(dentry, rcu_walk); if (IS_ERR(expiring)) return PTR_ERR(expiring); if (!expiring) - return autofs4_expire_wait(dentry, rcu_walk); + return autofs4_expire_wait(path, rcu_walk); else { + struct path this = { .mnt = path->mnt, .dentry = 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, just wait for it. */ - autofs4_expire_wait(expiring, 0); + autofs4_expire_wait(&this, 0); autofs4_del_expiring(expiring); dput(expiring); } @@ -354,7 +356,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path) * and the directory was removed, so just go ahead and try * the mount. */ - status = do_expire_wait(dentry, 0); + status = do_expire_wait(path, 0); if (status && status != -EAGAIN) return NULL; @@ -438,7 +440,7 @@ static int autofs4_d_manage(const struct path *path, bool rcu_walk) } /* Wait for pending expires */ - if (do_expire_wait(dentry, rcu_walk) == -ECHILD) + if (do_expire_wait(path, rcu_walk) == -ECHILD) return -ECHILD; /* -- cgit v1.1 From dd36a882e7ade2c642f8711426ad8e4b7009aaae Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Thu, 24 Nov 2016 08:03:42 +1100 Subject: autofs: change autofs4_wait() to take struct path In order to use the functions path_is_mountpoint() and path_has_submounts() autofs needs to pass a struct path in several places. Now change autofs4_wait() to take a struct path instead of a struct dentry. Link: http://lkml.kernel.org/r/20161011053413.27645.84666.stgit@pluto.themaw.net Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/autofs4/autofs_i.h | 3 ++- fs/autofs4/expire.c | 5 +++-- fs/autofs4/root.c | 16 ++++++++-------- fs/autofs4/waitq.c | 3 ++- 4 files changed, 15 insertions(+), 12 deletions(-) diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h index 4531152..c885daa 100644 --- a/fs/autofs4/autofs_i.h +++ b/fs/autofs4/autofs_i.h @@ -217,7 +217,8 @@ static inline int autofs_prepare_pipe(struct file *pipe) /* Queue management functions */ -int autofs4_wait(struct autofs_sb_info *, struct dentry *, enum autofs_notify); +int autofs4_wait(struct autofs_sb_info *, + const struct path *, enum autofs_notify); int autofs4_wait_release(struct autofs_sb_info *, autofs_wqt_t, int); void autofs4_catatonic_mode(struct autofs_sb_info *); diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c index 6ba6107..9c352da 100644 --- a/fs/autofs4/expire.c +++ b/fs/autofs4/expire.c @@ -526,7 +526,7 @@ retry: pr_debug("waiting for expire %p name=%pd\n", dentry, dentry); - status = autofs4_wait(sbi, dentry, NFY_NONE); + status = autofs4_wait(sbi, path, NFY_NONE); wait_for_completion(&ino->expire_complete); pr_debug("expire done status=%d\n", status); @@ -593,11 +593,12 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt, if (dentry) { struct autofs_info *ino = autofs4_dentry_ino(dentry); + struct path path = { .mnt = mnt, .dentry = dentry }; /* This is synchronous because it makes the daemon a * little easier */ - ret = autofs4_wait(sbi, dentry, NFY_EXPIRE); + ret = autofs4_wait(sbi, &path, NFY_EXPIRE); spin_lock(&sbi->fs_lock); /* avoid rapid-fire expire attempts if expiry fails */ diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 6b06337..0e98815 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -269,17 +269,17 @@ next: return NULL; } -static int autofs4_mount_wait(struct dentry *dentry, bool rcu_walk) +static int autofs4_mount_wait(const struct path *path, bool rcu_walk) { - struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); - struct autofs_info *ino = autofs4_dentry_ino(dentry); + struct autofs_sb_info *sbi = autofs4_sbi(path->dentry->d_sb); + struct autofs_info *ino = autofs4_dentry_ino(path->dentry); int status = 0; if (ino->flags & AUTOFS_INF_PENDING) { if (rcu_walk) return -ECHILD; - pr_debug("waiting for mount name=%pd\n", dentry); - status = autofs4_wait(sbi, dentry, NFY_MOUNT); + pr_debug("waiting for mount name=%pd\n", path->dentry); + status = autofs4_wait(sbi, path, NFY_MOUNT); pr_debug("mount wait done status=%d\n", status); } ino->last_used = jiffies; @@ -364,7 +364,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path) spin_lock(&sbi->fs_lock); if (ino->flags & AUTOFS_INF_PENDING) { spin_unlock(&sbi->fs_lock); - status = autofs4_mount_wait(dentry, 0); + status = autofs4_mount_wait(path, 0); if (status) return ERR_PTR(status); goto done; @@ -405,7 +405,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path) } ino->flags |= AUTOFS_INF_PENDING; spin_unlock(&sbi->fs_lock); - status = autofs4_mount_wait(dentry, 0); + status = autofs4_mount_wait(path, 0); spin_lock(&sbi->fs_lock); ino->flags &= ~AUTOFS_INF_PENDING; if (status) { @@ -447,7 +447,7 @@ static int autofs4_d_manage(const struct path *path, bool rcu_walk) * This dentry may be under construction so wait on mount * completion. */ - status = autofs4_mount_wait(dentry, rcu_walk); + status = autofs4_mount_wait(path, rcu_walk); if (status) return status; diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c index e44271d..38ef973 100644 --- a/fs/autofs4/waitq.c +++ b/fs/autofs4/waitq.c @@ -345,8 +345,9 @@ static int validate_request(struct autofs_wait_queue **wait, } int autofs4_wait(struct autofs_sb_info *sbi, - struct dentry *dentry, enum autofs_notify notify) + const struct path *path, enum autofs_notify notify) { + struct dentry *dentry = path->dentry; struct autofs_wait_queue *wq; struct qstr qstr; char *name; -- cgit v1.1 From cfaf86ab6ccdf0acf47ebe474a4a844114bc0e10 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Thu, 24 Nov 2016 08:03:42 +1100 Subject: autofs: use path_is_mountpoint() to fix unreliable d_mountpoint() checks If an automount mount is clone(2)ed into a file system that is propagation private, when it later expires in the originating namespace, subsequent calls to autofs ->d_automount() for that dentry in the original namespace will return ELOOP until the mount is umounted in the cloned namespace. Now that a struct path is available where needed use path_is_mountpoint() instead of d_mountpoint() so we don't get false positives when checking if a dentry is a mount point in the current namespace. Link: http://lkml.kernel.org/r/20161011053418.27645.15241.stgit@pluto.themaw.net Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/autofs4/root.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 0e98815..9355608 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -123,7 +123,7 @@ static int autofs4_dir_open(struct inode *inode, struct file *file) * it. */ spin_lock(&sbi->lookup_lock); - if (!d_mountpoint(dentry) && simple_empty(dentry)) { + if (!path_is_mountpoint(&file->f_path) && simple_empty(dentry)) { spin_unlock(&sbi->lookup_lock); return -ENOENT; } @@ -372,15 +372,15 @@ static struct vfsmount *autofs4_d_automount(struct path *path) /* * If the dentry is a symlink it's equivalent to a directory - * having d_mountpoint() true, so there's no need to call back - * to the daemon. + * having path_is_mountpoint() true, so there's no need to call + * back to the daemon. */ if (d_really_is_positive(dentry) && d_is_symlink(dentry)) { spin_unlock(&sbi->fs_lock); goto done; } - if (!d_mountpoint(dentry)) { + if (!path_is_mountpoint(path)) { /* * It's possible that user space hasn't removed directories * after umounting a rootless multi-mount, although it @@ -434,7 +434,7 @@ static int autofs4_d_manage(const struct path *path, bool rcu_walk) /* The daemon never waits. */ if (autofs4_oz_mode(sbi)) { - if (!d_mountpoint(dentry)) + if (!path_is_mountpoint(path)) return -EISDIR; return 0; } @@ -463,7 +463,7 @@ static int autofs4_d_manage(const struct path *path, bool rcu_walk) if (ino->flags & AUTOFS_INF_WANT_EXPIRE) return 0; - if (d_mountpoint(dentry)) + if (path_is_mountpoint(path)) return 0; inode = d_inode_rcu(dentry); if (inode && S_ISLNK(inode->i_mode)) @@ -490,7 +490,7 @@ static int autofs4_d_manage(const struct path *path, bool rcu_walk) * we can avoid needless calls ->d_automount() and avoid * an incorrect ELOOP error return. */ - if ((!d_mountpoint(dentry) && !simple_empty(dentry)) || + if ((!path_is_mountpoint(path) && !simple_empty(dentry)) || (d_really_is_positive(dentry) && d_is_symlink(dentry))) status = -EISDIR; } -- cgit v1.1 From 60359741473438f66fef7297d1fa2435640dbe79 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Thu, 24 Nov 2016 08:03:42 +1100 Subject: autofs: use path_has_submounts() to fix unreliable have_submount() checks If an automount mount is clone(2)ed into a file system that is propagation private, when it later expires in the originating namespace, subsequent calls to autofs ->d_automount() for that dentry in the original namespace will return ELOOP until the mount is umounted in the cloned namespace. Now that a struct path is available where needed use path_has_submounts() instead of have_submounts() so we don't get false positives when checking if a dentry is a mount point or contains mounts in the current namespace. Link: http://lkml.kernel.org/r/20161011053423.27645.91233.stgit@pluto.themaw.net Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/autofs4/dev-ioctl.c | 2 +- fs/autofs4/root.c | 14 +++++++------- fs/autofs4/waitq.c | 10 +++++++--- 3 files changed, 15 insertions(+), 11 deletions(-) diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c index 40c69f9..afacdaa 100644 --- a/fs/autofs4/dev-ioctl.c +++ b/fs/autofs4/dev-ioctl.c @@ -575,7 +575,7 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp, devid = new_encode_dev(dev); - err = have_submounts(path.dentry); + err = path_has_submounts(&path); if (follow_down_one(&path)) magic = path.dentry->d_sb->s_magic; diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 9355608..ce4e621 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -384,16 +384,16 @@ static struct vfsmount *autofs4_d_automount(struct path *path) /* * 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 trigger mounts. In this case we - * have no choice but to use the list_empty() check and + * should. For v5 path_has_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 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)) { + if (path_has_submounts(path)) { spin_unlock(&sbi->fs_lock); goto done; } diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c index 38ef973..1278335 100644 --- a/fs/autofs4/waitq.c +++ b/fs/autofs4/waitq.c @@ -250,8 +250,9 @@ autofs4_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr) static int validate_request(struct autofs_wait_queue **wait, struct autofs_sb_info *sbi, const struct qstr *qstr, - struct dentry *dentry, enum autofs_notify notify) + const struct path *path, enum autofs_notify notify) { + struct dentry *dentry = path->dentry; struct autofs_wait_queue *wq; struct autofs_info *ino; @@ -314,6 +315,7 @@ static int validate_request(struct autofs_wait_queue **wait, */ if (notify == NFY_MOUNT) { struct dentry *new = NULL; + struct path this; int valid = 1; /* @@ -333,7 +335,9 @@ static int validate_request(struct autofs_wait_queue **wait, dentry = new; } } - if (have_submounts(dentry)) + this.mnt = path->mnt; + this.dentry = dentry; + if (path_has_submounts(&this)) valid = 0; if (new) @@ -406,7 +410,7 @@ int autofs4_wait(struct autofs_sb_info *sbi, return -EINTR; } - ret = validate_request(&wq, sbi, &qstr, dentry, notify); + ret = validate_request(&wq, sbi, &qstr, path, notify); if (ret <= 0) { if (ret != -EINTR) mutex_unlock(&sbi->wq_mutex); -- cgit v1.1 From f74e7b33c37e5a7bae33bb73858c2766cb256626 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Thu, 24 Nov 2016 08:03:42 +1100 Subject: vfs: remove unused have_submounts() function Now that path_has_submounts() has been added have_submounts() is no longer used so remove it. Link: http://lkml.kernel.org/r/20161011053428.27645.12310.stgit@pluto.themaw.net Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/dcache.c | 33 --------------------------------- include/linux/dcache.h | 1 - 2 files changed, 34 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 8515875..2523783 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1273,39 +1273,6 @@ rename_retry: goto again; } -/* - * Search for at least 1 mount point in the dentry's subdirs. - * We descend to the next level whenever the d_subdirs - * list is non-empty and continue searching. - */ - -static enum d_walk_ret check_mount(void *data, struct dentry *dentry) -{ - int *ret = data; - if (d_mountpoint(dentry)) { - *ret = 1; - return D_WALK_QUIT; - } - return D_WALK_CONTINUE; -} - -/** - * have_submounts - check for mounts over a dentry - * @parent: dentry to check. - * - * Return true if the parent or its subdirectories contain - * a mount point - */ -int have_submounts(struct dentry *parent) -{ - int ret = 0; - - d_walk(parent, &ret, check_mount, NULL); - - return ret; -} -EXPORT_SYMBOL(have_submounts); - struct check_mount { struct vfsmount *mnt; unsigned int mounted; diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 0ffaf7a..c965e44 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -254,7 +254,6 @@ extern struct dentry *d_find_alias(struct inode *); extern void d_prune_aliases(struct inode *); /* test whether we have any submounts in a subdir tree */ -extern int have_submounts(struct dentry *); extern int path_has_submounts(const struct path *); /* -- cgit v1.1 From 455e8f1030de82b68ee4e82f71516f3692f5e626 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Mon, 28 Nov 2016 10:11:59 +0800 Subject: autofs - constify misc struct path instances Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Al Viro --- fs/autofs4/expire.c | 2 +- fs/autofs4/root.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c index 9c352da..13178bf 100644 --- a/fs/autofs4/expire.c +++ b/fs/autofs4/expire.c @@ -593,7 +593,7 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt, if (dentry) { struct autofs_info *ino = autofs4_dentry_ino(dentry); - struct path path = { .mnt = mnt, .dentry = dentry }; + const struct path path = { .mnt = mnt, .dentry = dentry }; /* This is synchronous because it makes the daemon a * little easier diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index ce4e621..82e8f6e 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -297,7 +297,7 @@ static int do_expire_wait(const struct path *path, bool rcu_walk) if (!expiring) return autofs4_expire_wait(path, rcu_walk); else { - struct path this = { .mnt = path->mnt, .dentry = expiring }; + const struct path this = { .mnt = path->mnt, .dentry = expiring }; /* * If we are racing with expire the request might not * be quite complete, but the directory has been removed -- cgit v1.1 From 1c4344a50d702307185cb98fb67bff938cd66aa0 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Mon, 28 Nov 2016 10:12:14 +0800 Subject: autofs - dont hold spin lock over direct mount expire Commit 7cbdb4a286 altered the autofs indirect mount expire to not hold a spin lock during the expire check. The direct mount expire needs the same treatment because to make autofs expires namespace aware may_umount_tree() needs to to use a similar method to may_umount() when checking if a mount tree is in use. This means may_umount_tree() will end up taking the namespace_sem for the check so the autofs direct mount expire won't be allowed to hold a spin lock over the check. Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval Signed-off-by: Al Viro --- fs/autofs4/expire.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c index 13178bf..57725d4 100644 --- a/fs/autofs4/expire.c +++ b/fs/autofs4/expire.c @@ -310,26 +310,29 @@ struct dentry *autofs4_expire_direct(struct super_block *sb, now = jiffies; 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) - goto out; if (!autofs4_direct_busy(mnt, root, timeout, do_now)) { + 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); + goto out; + } ino->flags |= AUTOFS_INF_WANT_EXPIRE; spin_unlock(&sbi->fs_lock); synchronize_rcu(); - spin_lock(&sbi->fs_lock); if (!autofs4_direct_busy(mnt, root, timeout, do_now)) { + spin_lock(&sbi->fs_lock); ino->flags |= AUTOFS_INF_EXPIRING; init_completion(&ino->expire_complete); spin_unlock(&sbi->fs_lock); return root; } + spin_lock(&sbi->fs_lock); ino->flags &= ~AUTOFS_INF_WANT_EXPIRE; + spin_unlock(&sbi->fs_lock); } out: - spin_unlock(&sbi->fs_lock); dput(root); return NULL; -- cgit v1.1