[PATCH] autofs4: fix false negative return from expire
Fix the case where an expire returns busy on a tree mount when it is in fact
not busy. This case was overlooked when the patch to prevent the expiring
away of "scaffolding" directories for tree mounts was applied.
The problem arises when a tree of mounts is a member of a map with other keys.
The current logic will not expire the tree if any other mount in the map is
busy. The solution is to maintain a "minimum" use count for each autofs
dentry and compare this to the actual dentry usage count during expire.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index eea2593..00da71d 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -55,6 +55,7 @@
struct autofs_sb_info *sbi;
unsigned long last_used;
+ atomic_t count;
mode_t mode;
size_t size;
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 165fe9e..053d92a 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -101,6 +101,7 @@
unsigned long timeout,
int do_now)
{
+ struct autofs_info *ino;
struct dentry *p;
DPRINTK("top %p %.*s",
@@ -110,14 +111,6 @@
if (!simple_positive(top))
return 1;
- /* Timeout of a tree mount is determined by its top dentry */
- if (!autofs4_can_expire(top, timeout, do_now))
- return 1;
-
- /* Is someone visiting anywhere in the tree ? */
- if (may_umount_tree(mnt))
- return 1;
-
spin_lock(&dcache_lock);
for (p = top; p; p = next_dentry(p, top)) {
/* Negative dentry - give up */
@@ -130,17 +123,40 @@
p = dget(p);
spin_unlock(&dcache_lock);
+ /*
+ * Is someone visiting anywhere in the subtree ?
+ * If there's no mount we need to check the usage
+ * count for the autofs dentry.
+ */
+ ino = autofs4_dentry_ino(p);
if (d_mountpoint(p)) {
- /* First busy => tree busy */
if (autofs4_mount_busy(mnt, p)) {
dput(p);
return 1;
}
+ } else {
+ unsigned int ino_count = atomic_read(&ino->count);
+
+ /* allow for dget above and top is already dgot */
+ if (p == top)
+ ino_count += 2;
+ else
+ ino_count++;
+
+ if (atomic_read(&p->d_count) > ino_count) {
+ dput(p);
+ return 1;
+ }
}
dput(p);
spin_lock(&dcache_lock);
}
spin_unlock(&dcache_lock);
+
+ /* Timeout of a tree mount is ultimately determined by its top dentry */
+ if (!autofs4_can_expire(top, timeout, do_now))
+ return 1;
+
return 0;
}
diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index 1ad98d4..2335b1d 100644
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -46,6 +46,7 @@
ino->size = 0;
ino->last_used = jiffies;
+ atomic_set(&ino->count, 0);
ino->sbi = sbi;
@@ -64,10 +65,19 @@
void autofs4_free_ino(struct autofs_info *ino)
{
+ struct autofs_info *p_ino;
+
if (ino->dentry) {
ino->dentry->d_fsdata = NULL;
- if (ino->dentry->d_inode)
+ if (ino->dentry->d_inode) {
+ struct dentry *parent = ino->dentry->d_parent;
+ if (atomic_dec_and_test(&ino->count)) {
+ p_ino = autofs4_dentry_ino(parent);
+ if (p_ino && parent != ino->dentry)
+ atomic_dec(&p_ino->count);
+ }
dput(ino->dentry);
+ }
ino->dentry = NULL;
}
if (ino->free)
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index c7ff357..d196712 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -490,6 +490,7 @@
{
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
+ struct autofs_info *p_ino;
struct inode *inode;
char *cp;
@@ -523,6 +524,10 @@
dentry->d_fsdata = ino;
ino->dentry = dget(dentry);
+ atomic_inc(&ino->count);
+ p_ino = autofs4_dentry_ino(dentry->d_parent);
+ if (p_ino && dentry->d_parent != dentry)
+ atomic_inc(&p_ino->count);
ino->inode = inode;
dir->i_mtime = CURRENT_TIME;
@@ -549,11 +554,17 @@
{
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
+ struct autofs_info *p_ino;
/* This allows root to remove symlinks */
if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
return -EACCES;
+ if (atomic_dec_and_test(&ino->count)) {
+ p_ino = autofs4_dentry_ino(dentry->d_parent);
+ if (p_ino && dentry->d_parent != dentry)
+ atomic_dec(&p_ino->count);
+ }
dput(ino->dentry);
dentry->d_inode->i_size = 0;
@@ -570,6 +581,7 @@
{
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
+ struct autofs_info *p_ino;
if (!autofs4_oz_mode(sbi))
return -EACCES;
@@ -584,8 +596,12 @@
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
+ if (atomic_dec_and_test(&ino->count)) {
+ p_ino = autofs4_dentry_ino(dentry->d_parent);
+ if (p_ino && dentry->d_parent != dentry)
+ atomic_dec(&p_ino->count);
+ }
dput(ino->dentry);
-
dentry->d_inode->i_size = 0;
dentry->d_inode->i_nlink = 0;
@@ -599,6 +615,7 @@
{
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
+ struct autofs_info *p_ino;
struct inode *inode;
if ( !autofs4_oz_mode(sbi) )
@@ -621,6 +638,10 @@
dentry->d_fsdata = ino;
ino->dentry = dget(dentry);
+ atomic_inc(&ino->count);
+ p_ino = autofs4_dentry_ino(dentry->d_parent);
+ if (p_ino && dentry->d_parent != dentry)
+ atomic_inc(&p_ino->count);
ino->inode = inode;
dir->i_nlink++;
dir->i_mtime = CURRENT_TIME;
