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SubjectRe: [PATCH 4/4] autofs: add comment about autofs_mountpoint_changed()
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One nit, below.
Vince

On Thu, Mar 26, 2020 at 01:23:36PM +0800, Ian Kent wrote:
>The function autofs_mountpoint_changed() is unusual, add a comment
>about two cases for which it is used.
>
>Signed-off-by: Ian Kent <raven@themaw.net>
>---
> fs/autofs/root.c | 21 ++++++++++++++++++---
> 1 file changed, 18 insertions(+), 3 deletions(-)
>
>diff --git a/fs/autofs/root.c b/fs/autofs/root.c
>index 308cc49aca1d..a972bbaecb46 100644
>--- a/fs/autofs/root.c
>+++ b/fs/autofs/root.c
>@@ -280,9 +280,24 @@ static struct dentry *autofs_mountpoint_changed(struct path *path)
> struct dentry *dentry = path->dentry;
> struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
>
>- /*
>- * If this is an indirect mount the dentry could have gone away
>- * as a result of an expire and a new one created.
>+ /* If this is an indirect mount the dentry could have gone away
>+ * and a new one created.
>+ *
>+ * This is unusual and I can't remember the case for which it
>+ * was originally added now. But a example of how this can

'an' example

>+ * happen is an autofs indirect mount that has the "browse"
>+ * option set and also has the "symlink" option in the autofs
>+ * map entry. In this case the daemon will remove the browse
>+ * directory and create a symlink as the mount (pointing to a
>+ * local path) leaving the struct path stale.
>+ *
>+ * Another not so obvious case is when a mount in an autofs
>+ * indirect mount that uses the "nobrowse" option is being
>+ * expired and the mount has been umounted but the mount point
>+ * directory remains when a stat family system call is made.
>+ * In this case the mount point is removed (by the daemon) and
>+ * a new mount triggered leading to a stale dentry in the struct
>+ * path of the waiting process.
> */
> if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
> struct dentry *parent = dentry->d_parent;
>

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