Commit 9b1e3afd authored by Ian Kent's avatar Ian Kent Committed by Linus Torvalds

[PATCH] autofs4: avoid panic on bind mount of autofs owned directory

While this is not a solution to bind and move mounts on autofs owned
directories it is necessary to fix the trady error handling.

At least it avoids the kernel panic I observed checking out bug #4589.
Signed-off-by: default avatarIan Kent <raven@themaw.net>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 88187605
......@@ -185,6 +185,19 @@ int autofs4_wait(struct autofs_sb_info *,struct dentry *, enum autofs_notify);
int autofs4_wait_release(struct autofs_sb_info *,autofs_wqt_t,int);
void autofs4_catatonic_mode(struct autofs_sb_info *);
static inline int autofs4_follow_mount(struct vfsmount **mnt, struct dentry **dentry)
{
int res = 0;
while (d_mountpoint(*dentry)) {
int followed = follow_down(mnt, dentry);
if (!followed)
break;
res = 1;
}
return res;
}
static inline int simple_positive(struct dentry *dentry)
{
return dentry->d_inode && !d_unhashed(dentry);
......
......@@ -56,12 +56,9 @@ static int autofs4_check_mount(struct vfsmount *mnt, struct dentry *dentry)
mntget(mnt);
dget(dentry);
if (!follow_down(&mnt, &dentry))
if (!autofs4_follow_mount(&mnt, &dentry))
goto done;
while (d_mountpoint(dentry) && follow_down(&mnt, &dentry))
;
/* This is an autofs submount, we can't expire it */
if (is_autofs4_dentry(dentry))
goto done;
......
......@@ -205,7 +205,11 @@ static int autofs4_dir_open(struct inode *inode, struct file *file)
struct vfsmount *fp_mnt = mntget(mnt);
struct dentry *fp_dentry = dget(dentry);
while (follow_down(&fp_mnt, &fp_dentry) && d_mountpoint(fp_dentry));
if (!autofs4_follow_mount(&fp_mnt, &fp_dentry)) {
dput(fp_dentry);
mntput(fp_mnt);
return -ENOENT;
}
fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
status = PTR_ERR(fp);
......
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