David Howells <dhowells@xxxxxxxxxx> writes:
>> Get a grip, people. Stop over-analyzing things. Stop bothering to
>> mention what Solaris does, when the *MUCH* bigger issue is what
>> *Linux* has done for years and years.
>
> So the word is Linux may not change it's behaviour in this regard from what
> existed prior to the d_automount patch, period?
You can change behavior if it won't cause regressions. So fix userspace
first, introduce change afterwards.
>> Stop saying "we'll revert Miklos patch" in the same sentence where you
>> then seem to not even understand that the *original* behavior was the
>> one that Miklos patch re-introduced.
>
> Miklos's patch did *NOT* re-introduce the original behaviour. It introduced a
> third state. It merely moved the regression and brought about a more serious
> one.
Yes, and there have been lots of proposals on how to fix it. There just
doesn't seem to be a consensus.
I suggest that we first restore the original behavior for all
filesystems. And it doesn't mean all the d_automount infrastructure has
to be thrown out. A really simple fix is to pass the lookup flags (or
some derived automount flags) to d_automount and fix up the very few
instances to reflect the old semantics. Untested patch attached.
Thanks,
Miklos
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 6533807..5fe8124 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -19,7 +19,7 @@ prototypes:
void (*d_release)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen);
- struct vfsmount *(*d_automount)(struct path *path);
+ struct vfsmount *(*d_automount)(struct path *path, int);
int (*d_manage)(struct dentry *, bool);
locking rules:
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 52d8fb8..15e6a50 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -894,7 +894,7 @@ struct dentry_operations {
void (*d_release)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
char *(*d_dname)(struct dentry *, char *, int);
- struct vfsmount *(*d_automount)(struct path *);
+ struct vfsmount *(*d_automount)(struct path *, int);
int (*d_manage)(struct dentry *, bool);
};
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index d2b0888..e687963 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -592,7 +592,7 @@ extern const struct inode_operations afs_mntpt_inode_operations;
extern const struct inode_operations afs_autocell_inode_operations;
extern const struct file_operations afs_mntpt_file_operations;
-extern struct vfsmount *afs_d_automount(struct path *);
+extern struct vfsmount *afs_d_automount(struct path *, int);
extern int afs_mntpt_check_symlink(struct afs_vnode *, struct key *);
extern void afs_mntpt_kill_timer(void);
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
index aa59184..aba1c56 100644
--- a/fs/afs/mntpt.c
+++ b/fs/afs/mntpt.c
@@ -238,12 +238,19 @@ error_no_devname:
/*
* handle an automount point
*/
-struct vfsmount *afs_d_automount(struct path *path)
+struct vfsmount *afs_d_automount(struct path *path, int lookup_flags)
{
struct vfsmount *newmnt;
_enter("{%s,%s}", path->mnt->mnt_devname, path->dentry->d_name.name);
+ /*
+ * We don't want to mount if someone's just doing an lstat - unless
+ * they're stat'ing a directory and appended a '/' to the name.
+ */
+ if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | LOOKUP_FOLLOW)))
+ return ERR_PTR(-EISDIR);
+
newmnt = afs_mntpt_do_automount(path->dentry);
if (IS_ERR(newmnt))
return newmnt;
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index f55ae23..5335e08 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -322,7 +322,7 @@ static struct dentry *autofs4_mountpoint_changed(struct path *path)
return path->dentry;
}
-static struct vfsmount *autofs4_d_automount(struct path *path)
+static struct vfsmount *autofs4_d_automount(struct path *path, int lookup_flags)
{
struct dentry *dentry = path->dentry;
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
@@ -332,6 +332,22 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
DPRINTK("dentry=%p %.*s",
dentry, dentry->d_name.len, dentry->d_name.name);
+ /* We don't want to mount if someone's just doing a stat -
+ * unless they're stat'ing a directory and appended a '/' to
+ * the name.
+ *
+ * We do, however, want to mount if someone wants to open or
+ * create a file of any type under the mountpoint, wants to
+ * traverse through the mountpoint or wants to open the
+ * mounted directory. Also, autofs may mark negative dentries
+ * as being automount points. These will need the attentions
+ * of the daemon to instantiate them before they can be used.
+ */
+ if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
+ LOOKUP_OPEN | LOOKUP_CREATE)) &&
+ path->dentry->d_inode)
+ return ERR_PTR(-EISDIR);
+
/* The daemon never triggers a mount. */
if (autofs4_oz_mode(sbi))
return NULL;
diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index 6873bb6..2ad1dcb 100644
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -347,12 +347,19 @@ cdda_exit:
/*
* Attempt to automount the referral
*/
-struct vfsmount *cifs_dfs_d_automount(struct path *path)
+struct vfsmount *cifs_dfs_d_automount(struct path *path, int lookup_flags)
{
struct vfsmount *newmnt;
cFYI(1, "in %s", __func__);
+ /*
+ * We don't want to mount if someone's just doing an lstat - unless
+ * they're stat'ing a directory and appended a '/' to the name.
+ */
+ if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | LOOKUP_FOLLOW)))
+ return ERR_PTR(-EISDIR);
+
newmnt = cifs_dfs_do_automount(path->dentry);
if (IS_ERR(newmnt)) {
cFYI(1, "leaving %s [automount failed]" , __func__);
diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index 95da802..0cd1286 100644
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -101,7 +101,7 @@ extern const struct dentry_operations cifs_dentry_ops;
extern const struct dentry_operations cifs_ci_dentry_ops;
#ifdef CONFIG_CIFS_DFS_UPCALL
-extern struct vfsmount *cifs_dfs_d_automount(struct path *path);
+extern struct vfsmount *cifs_dfs_d_automount(struct path *path, int lookup_flags);
#else
#define cifs_dfs_d_automount NULL
#endif
diff --git a/fs/namei.c b/fs/namei.c
index f478836..a637893 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -727,27 +727,11 @@ static int follow_automount(struct path *path, unsigned flags,
if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_PARENT))
return -EISDIR; /* we actually want to stop here */
- /* We don't want to mount if someone's just doing a stat -
- * unless they're stat'ing a directory and appended a '/' to
- * the name.
- *
- * We do, however, want to mount if someone wants to open or
- * create a file of any type under the mountpoint, wants to
- * traverse through the mountpoint or wants to open the
- * mounted directory. Also, autofs may mark negative dentries
- * as being automount points. These will need the attentions
- * of the daemon to instantiate them before they can be used.
- */
- if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
- LOOKUP_OPEN | LOOKUP_CREATE)) &&
- path->dentry->d_inode)
- return -EISDIR;
-
current->total_link_count++;
if (current->total_link_count >= 40)
return -ELOOP;
- mnt = path->dentry->d_op->d_automount(path);
+ mnt = path->dentry->d_op->d_automount(path, flags);
if (IS_ERR(mnt)) {
/*
* The filesystem is allowed to return -EISDIR here to indicate
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index ab12913..904779f 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -276,7 +276,7 @@ extern void nfs_sb_deactive(struct super_block *sb);
/* namespace.c */
extern char *nfs_path(char **p, struct dentry *dentry,
char *buffer, ssize_t buflen);
-extern struct vfsmount *nfs_d_automount(struct path *path);
+extern struct vfsmount *nfs_d_automount(struct path *path, int lookup_flags);
#ifdef CONFIG_NFS_V4
rpc_authflavor_t nfs_find_best_sec(struct nfs4_secinfo_flavors *);
#endif
diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index 8102391..0c0ef6a 100644
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -223,7 +223,7 @@ static inline int nfs_lookup_with_sec(struct nfs_server *server,
* situation, and that different filesystems may want to use
* different security flavours.
*/
-struct vfsmount *nfs_d_automount(struct path *path)
+struct vfsmount *nfs_d_automount(struct path *path, int lookup_flags)
{
struct vfsmount *mnt;
struct nfs_server *server = NFS_SERVER(path->dentry->d_inode);
@@ -235,6 +235,14 @@ struct vfsmount *nfs_d_automount(struct path *path)
dprintk("--> nfs_d_automount()\n");
+ /*
+ * We don't want to mount if someone's just doing an lstat - unless
+ * they're stat'ing a directory and appended a '/' to the name.
+ */
+ mnt = ERR_PTR(-EISDIR);
+ if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | LOOKUP_FOLLOW)))
+ goto out_nofree;
+
mnt = ERR_PTR(-ESTALE);
if (IS_ROOT(path->dentry))
goto out_nofree;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 62157c0..deeb5b2 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -167,7 +167,7 @@ struct dentry_operations {
void (*d_release)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
char *(*d_dname)(struct dentry *, char *, int);
- struct vfsmount *(*d_automount)(struct path *);
+ struct vfsmount *(*d_automount)(struct path *, int);
int (*d_manage)(struct dentry *, bool);
} ____cacheline_aligned;
--
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