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Message-ID: <20140714105359.4415aab4@notabene.brown>
Date: Mon, 14 Jul 2014 10:53:59 +1000
From: NeilBrown <neilb@...e.de>
To: Ian Kent <raven@...maw.net>
Cc: autofs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6 v2] autofs4: factor should_expire() out of
autofs4_expire_indirect.
Here is a revised version of this one patch.
This one fixes a problem with refcounts on dentry and adds a comment to
clarify the behaviour of should_expire().
thanks,
NeilBrown
From: NeilBrown <neilb@...e.de>Date: Tue, 8 Jul 2014 17:14:53 +1000
Subject: [PATCH] autofs4: factor should_expire() out of autofs4_expire_indirect.
Future patch will potentially call this twice, so make it
separate.
Signed-off-by: NeilBrown <neilb@...e.de>
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 7e2f22ce6954..402ee7f1461a 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -345,6 +345,89 @@ out:
return NULL;
}
+/* Check if 'dentry' should expire, or return a nearby
+ * dentry that is suitable.
+ * If returned dentry is different from arg dentry,
+ * then a dget() reference was taken, else not.
+ */
+static struct dentry *should_expire(struct dentry *dentry,
+ struct vfsmount *mnt,
+ unsigned long timeout,
+ int how)
+{
+ int do_now = how & AUTOFS_EXP_IMMEDIATE;
+ int exp_leaves = how & AUTOFS_EXP_LEAVES;
+ struct autofs_info *ino = autofs4_dentry_ino(dentry);
+ unsigned int ino_count;
+
+ /* No point expiring a pending mount */
+ if (ino->flags & AUTOFS_INF_PENDING)
+ return NULL;
+
+ /*
+ * Case 1: (i) indirect mount or top level pseudo direct mount
+ * (autofs-4.1).
+ * (ii) indirect mount with offset mount, check the "/"
+ * offset (autofs-5.0+).
+ */
+ if (d_mountpoint(dentry)) {
+ DPRINTK("checking mountpoint %p %.*s",
+ dentry, (int)dentry->d_name.len, dentry->d_name.name);
+
+ /* Can we umount this guy */
+ if (autofs4_mount_busy(mnt, dentry))
+ return NULL;
+
+ /* Can we expire this guy */
+ if (autofs4_can_expire(dentry, timeout, do_now))
+ return dentry;
+ return NULL;
+ }
+
+ if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)) {
+ DPRINTK("checking symlink %p %.*s",
+ dentry, (int)dentry->d_name.len, dentry->d_name.name);
+ /*
+ * A symlink can't be "busy" in the usual sense so
+ * just check last used for expire timeout.
+ */
+ if (autofs4_can_expire(dentry, timeout, do_now))
+ return dentry;
+ return NULL;
+ }
+
+ if (simple_empty(dentry))
+ return NULL;
+
+ /* Case 2: tree mount, expire iff entire tree is not busy */
+ if (!exp_leaves) {
+ /* Path walk currently on this dentry? */
+ ino_count = atomic_read(&ino->count) + 1;
+ if (d_count(dentry) > ino_count)
+ return NULL;
+
+ if (!autofs4_tree_busy(mnt, dentry, timeout, do_now))
+ return dentry;
+ /*
+ * Case 3: pseudo direct mount, expire individual leaves
+ * (autofs-4.1).
+ */
+ } else {
+ /* Path walk currently on this dentry? */
+ struct dentry *expired;
+ ino_count = atomic_read(&ino->count) + 1;
+ if (d_count(dentry) > ino_count)
+ return NULL;
+
+ expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
+ if (expired) {
+ if (expired == dentry)
+ dput(dentry);
+ return dentry;
+ }
+ }
+ return NULL;
+}
/*
* Find an eligible tree to time-out
* A tree is eligible if :-
@@ -359,11 +442,8 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
unsigned long timeout;
struct dentry *root = sb->s_root;
struct dentry *dentry;
- struct dentry *expired = NULL;
- int do_now = how & AUTOFS_EXP_IMMEDIATE;
- int exp_leaves = how & AUTOFS_EXP_LEAVES;
+ struct dentry *expired;
struct autofs_info *ino;
- unsigned int ino_count;
if (!root)
return NULL;
@@ -374,78 +454,12 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
dentry = NULL;
while ((dentry = get_next_positive_subdir(dentry, root))) {
spin_lock(&sbi->fs_lock);
- ino = autofs4_dentry_ino(dentry);
- /* No point expiring a pending mount */
- if (ino->flags & AUTOFS_INF_PENDING)
- goto next;
-
- /*
- * Case 1: (i) indirect mount or top level pseudo direct mount
- * (autofs-4.1).
- * (ii) indirect mount with offset mount, check the "/"
- * offset (autofs-5.0+).
- */
- if (d_mountpoint(dentry)) {
- DPRINTK("checking mountpoint %p %.*s",
- dentry, (int)dentry->d_name.len, dentry->d_name.name);
-
- /* Can we umount this guy */
- if (autofs4_mount_busy(mnt, dentry))
- goto next;
-
- /* Can we expire this guy */
- if (autofs4_can_expire(dentry, timeout, do_now)) {
- expired = dentry;
- goto found;
- }
- goto next;
- }
-
- if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)) {
- DPRINTK("checking symlink %p %.*s",
- dentry, (int)dentry->d_name.len, dentry->d_name.name);
- /*
- * A symlink can't be "busy" in the usual sense so
- * just check last used for expire timeout.
- */
- if (autofs4_can_expire(dentry, timeout, do_now)) {
- expired = dentry;
- goto found;
- }
- goto next;
- }
-
- if (simple_empty(dentry))
- goto next;
-
- /* Case 2: tree mount, expire iff entire tree is not busy */
- if (!exp_leaves) {
- /* Path walk currently on this dentry? */
- ino_count = atomic_read(&ino->count) + 1;
- if (d_count(dentry) > ino_count)
- goto next;
-
- if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
- expired = dentry;
- goto found;
- }
- /*
- * Case 3: pseudo direct mount, expire individual leaves
- * (autofs-4.1).
- */
- } else {
- /* Path walk currently on this dentry? */
- ino_count = atomic_read(&ino->count) + 1;
- if (d_count(dentry) > ino_count)
- goto next;
-
- expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
- if (expired) {
+ expired = should_expire(dentry, mnt, timeout, how);
+ if (expired) {
+ if (expired != dentry)
dput(dentry);
- goto found;
- }
+ goto found;
}
-next:
spin_unlock(&sbi->fs_lock);
}
return NULL;
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