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-rw-r--r--fs/autofs4/expire.c358
1 files changed, 358 insertions, 0 deletions
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
new file mode 100644
index 00000000000..31540a6404d
--- /dev/null
+++ b/fs/autofs4/expire.c
@@ -0,0 +1,358 @@
+/* -*- c -*- --------------------------------------------------------------- *
+ *
+ * linux/fs/autofs/expire.c
+ *
+ * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
+ * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
+ * Copyright 2001-2003 Ian Kent <raven@themaw.net>
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * ------------------------------------------------------------------------- */
+
+#include "autofs_i.h"
+
+static unsigned long now;
+
+/* Check if a dentry can be expired return 1 if it can else return 0 */
+static inline int autofs4_can_expire(struct dentry *dentry,
+ unsigned long timeout, int do_now)
+{
+ struct autofs_info *ino = autofs4_dentry_ino(dentry);
+
+ /* dentry in the process of being deleted */
+ if (ino == NULL)
+ return 0;
+
+ /* No point expiring a pending mount */
+ if (dentry->d_flags & DCACHE_AUTOFS_PENDING)
+ return 0;
+
+ if (!do_now) {
+ /* Too young to die */
+ if (time_after(ino->last_used + timeout, now))
+ return 0;
+
+ /* update last_used here :-
+ - obviously makes sense if it is in use now
+ - less obviously, prevents rapid-fire expire
+ attempts if expire fails the first time */
+ ino->last_used = now;
+ }
+
+ return 1;
+}
+
+/* Check a mount point for busyness return 1 if not busy, otherwise */
+static int autofs4_check_mount(struct vfsmount *mnt, struct dentry *dentry)
+{
+ int status = 0;
+
+ DPRINTK("dentry %p %.*s",
+ dentry, (int)dentry->d_name.len, dentry->d_name.name);
+
+ mntget(mnt);
+ dget(dentry);
+
+ if (!follow_down(&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;
+
+ /* The big question */
+ if (may_umount_tree(mnt) == 0)
+ status = 1;
+done:
+ DPRINTK("returning = %d", status);
+ mntput(mnt);
+ dput(dentry);
+ return status;
+}
+
+/* Check a directory tree of mount points for busyness
+ * The tree is not busy iff no mountpoints are busy
+ * Return 1 if the tree is busy or 0 otherwise
+ */
+static int autofs4_check_tree(struct vfsmount *mnt,
+ struct dentry *top,
+ unsigned long timeout,
+ int do_now)
+{
+ struct dentry *this_parent = top;
+ struct list_head *next;
+
+ DPRINTK("parent %p %.*s",
+ top, (int)top->d_name.len, top->d_name.name);
+
+ /* Negative dentry - give up */
+ if (!simple_positive(top))
+ return 0;
+
+ /* Timeout of a tree mount is determined by its top dentry */
+ if (!autofs4_can_expire(top, timeout, do_now))
+ return 0;
+
+ spin_lock(&dcache_lock);
+repeat:
+ next = this_parent->d_subdirs.next;
+resume:
+ while (next != &this_parent->d_subdirs) {
+ struct dentry *dentry = list_entry(next, struct dentry, d_child);
+
+ /* Negative dentry - give up */
+ if (!simple_positive(dentry)) {
+ next = next->next;
+ continue;
+ }
+
+ DPRINTK("dentry %p %.*s",
+ dentry, (int)dentry->d_name.len, dentry->d_name.name);
+
+ if (!simple_empty_nolock(dentry)) {
+ this_parent = dentry;
+ goto repeat;
+ }
+
+ dentry = dget(dentry);
+ spin_unlock(&dcache_lock);
+
+ if (d_mountpoint(dentry)) {
+ /* First busy => tree busy */
+ if (!autofs4_check_mount(mnt, dentry)) {
+ dput(dentry);
+ return 0;
+ }
+ }
+
+ dput(dentry);
+ spin_lock(&dcache_lock);
+ next = next->next;
+ }
+
+ if (this_parent != top) {
+ next = this_parent->d_child.next;
+ this_parent = this_parent->d_parent;
+ goto resume;
+ }
+ spin_unlock(&dcache_lock);
+
+ return 1;
+}
+
+static struct dentry *autofs4_check_leaves(struct vfsmount *mnt,
+ struct dentry *parent,
+ unsigned long timeout,
+ int do_now)
+{
+ struct dentry *this_parent = parent;
+ struct list_head *next;
+
+ DPRINTK("parent %p %.*s",
+ parent, (int)parent->d_name.len, parent->d_name.name);
+
+ spin_lock(&dcache_lock);
+repeat:
+ next = this_parent->d_subdirs.next;
+resume:
+ while (next != &this_parent->d_subdirs) {
+ struct dentry *dentry = list_entry(next, struct dentry, d_child);
+
+ /* Negative dentry - give up */
+ if (!simple_positive(dentry)) {
+ next = next->next;
+ continue;
+ }
+
+ DPRINTK("dentry %p %.*s",
+ dentry, (int)dentry->d_name.len, dentry->d_name.name);
+
+ if (!list_empty(&dentry->d_subdirs)) {
+ this_parent = dentry;
+ goto repeat;
+ }
+
+ dentry = dget(dentry);
+ spin_unlock(&dcache_lock);
+
+ if (d_mountpoint(dentry)) {
+ /* Can we expire this guy */
+ if (!autofs4_can_expire(dentry, timeout, do_now))
+ goto cont;
+
+ /* Can we umount this guy */
+ if (autofs4_check_mount(mnt, dentry))
+ return dentry;
+
+ }
+cont:
+ dput(dentry);
+ spin_lock(&dcache_lock);
+ next = next->next;
+ }
+
+ if (this_parent != parent) {
+ next = this_parent->d_child.next;
+ this_parent = this_parent->d_parent;
+ goto resume;
+ }
+ spin_unlock(&dcache_lock);
+
+ return NULL;
+}
+
+/*
+ * Find an eligible tree to time-out
+ * A tree is eligible if :-
+ * - it is unused by any user process
+ * - it has been unused for exp_timeout time
+ */
+static struct dentry *autofs4_expire(struct super_block *sb,
+ struct vfsmount *mnt,
+ struct autofs_sb_info *sbi,
+ int how)
+{
+ unsigned long timeout;
+ struct dentry *root = sb->s_root;
+ struct dentry *expired = NULL;
+ struct list_head *next;
+ int do_now = how & AUTOFS_EXP_IMMEDIATE;
+ int exp_leaves = how & AUTOFS_EXP_LEAVES;
+
+ if ( !sbi->exp_timeout || !root )
+ return NULL;
+
+ now = jiffies;
+ timeout = sbi->exp_timeout;
+
+ spin_lock(&dcache_lock);
+ next = root->d_subdirs.next;
+
+ /* On exit from the loop expire is set to a dgot dentry
+ * to expire or it's NULL */
+ while ( next != &root->d_subdirs ) {
+ struct dentry *dentry = list_entry(next, struct dentry, d_child);
+
+ /* Negative dentry - give up */
+ if ( !simple_positive(dentry) ) {
+ next = next->next;
+ continue;
+ }
+
+ dentry = dget(dentry);
+ spin_unlock(&dcache_lock);
+
+ /* Case 1: indirect mount or top level direct mount */
+ if (d_mountpoint(dentry)) {
+ DPRINTK("checking mountpoint %p %.*s",
+ dentry, (int)dentry->d_name.len, dentry->d_name.name);
+
+ /* Can we expire this guy */
+ if (!autofs4_can_expire(dentry, timeout, do_now))
+ goto next;
+
+ /* Can we umount this guy */
+ if (autofs4_check_mount(mnt, dentry)) {
+ expired = dentry;
+ break;
+ }
+ goto next;
+ }
+
+ if ( simple_empty(dentry) )
+ goto next;
+
+ /* Case 2: tree mount, expire iff entire tree is not busy */
+ if (!exp_leaves) {
+ if (autofs4_check_tree(mnt, dentry, timeout, do_now)) {
+ expired = dentry;
+ break;
+ }
+ /* Case 3: direct mount, expire individual leaves */
+ } else {
+ expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
+ if (expired) {
+ dput(dentry);
+ break;
+ }
+ }
+next:
+ dput(dentry);
+ spin_lock(&dcache_lock);
+ next = next->next;
+ }
+
+ if ( expired ) {
+ DPRINTK("returning %p %.*s",
+ expired, (int)expired->d_name.len, expired->d_name.name);
+ spin_lock(&dcache_lock);
+ list_del(&expired->d_parent->d_subdirs);
+ list_add(&expired->d_parent->d_subdirs, &expired->d_child);
+ spin_unlock(&dcache_lock);
+ return expired;
+ }
+ spin_unlock(&dcache_lock);
+
+ return NULL;
+}
+
+/* Perform an expiry operation */
+int autofs4_expire_run(struct super_block *sb,
+ struct vfsmount *mnt,
+ struct autofs_sb_info *sbi,
+ struct autofs_packet_expire __user *pkt_p)
+{
+ struct autofs_packet_expire pkt;
+ struct dentry *dentry;
+
+ memset(&pkt,0,sizeof pkt);
+
+ pkt.hdr.proto_version = sbi->version;
+ pkt.hdr.type = autofs_ptype_expire;
+
+ if ((dentry = autofs4_expire(sb, mnt, sbi, 0)) == NULL)
+ return -EAGAIN;
+
+ pkt.len = dentry->d_name.len;
+ memcpy(pkt.name, dentry->d_name.name, pkt.len);
+ pkt.name[pkt.len] = '\0';
+ dput(dentry);
+
+ if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
+ return -EFAULT;
+
+ return 0;
+}
+
+/* Call repeatedly until it returns -EAGAIN, meaning there's nothing
+ more to be done */
+int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt,
+ struct autofs_sb_info *sbi, int __user *arg)
+{
+ struct dentry *dentry;
+ int ret = -EAGAIN;
+ int do_now = 0;
+
+ if (arg && get_user(do_now, arg))
+ return -EFAULT;
+
+ if ((dentry = autofs4_expire(sb, mnt, sbi, do_now)) != NULL) {
+ struct autofs_info *de_info = autofs4_dentry_ino(dentry);
+
+ /* This is synchronous because it makes the daemon a
+ little easier */
+ de_info->flags |= AUTOFS_INF_EXPIRING;
+ ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
+ de_info->flags &= ~AUTOFS_INF_EXPIRING;
+ dput(dentry);
+ }
+
+ return ret;
+}
+
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