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| author | Ian Kent <raven@themaw.net> | 2022-07-08 03:43:18 +0200 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-07-18 02:31:42 +0200 |
| commit | ba97a0a3a31a2451607ebf601c0b7c4b1322ce9a (patch) | |
| tree | 7e86630bebba7fb0b7e1e7a6aad5569bce5c594b /fs/autofs/root.c | |
| parent | autofs: use dentry info count instead of simple_empty() (diff) | |
| download | linux-ba97a0a3a31a2451607ebf601c0b7c4b1322ce9a.tar.xz linux-ba97a0a3a31a2451607ebf601c0b7c4b1322ce9a.zip | |
autofs: add comment about autofs_mountpoint_changed()
The function autofs_mountpoint_changed() is unusual, add a comment about
two cases for which it is needed.
Link: https://lkml.kernel.org/r/165724459804.30914.10974834416046555127.stgit@donald.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'fs/autofs/root.c')
| -rw-r--r-- | fs/autofs/root.c | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/fs/autofs/root.c b/fs/autofs/root.c index e0fa71eb5c05..ca03c1cae2be 100644 --- a/fs/autofs/root.c +++ b/fs/autofs/root.c @@ -291,9 +291,26 @@ 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 an example of how this can + * 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 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 at the same time as a path walk. If the mount has + * been umounted but the mount point directory seen before + * becoming unhashed (during a lockless path walk) when a stat + * family system call is made the mount won't be re-mounted as + * it should. In this case the mount point that's been removed + * (by the daemon) will be stale and the a new mount point + * dentry created. */ if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) { struct dentry *parent = dentry->d_parent; |