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