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path: root/fs/autofs4/expire.c
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Diffstat (limited to 'fs/autofs4/expire.c')
-rw-r--r--fs/autofs4/expire.c210
1 files changed, 127 insertions, 83 deletions
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 8fa3895cda02..683a5b9ce22a 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -30,12 +30,6 @@ static inline int autofs4_can_expire(struct dentry *dentry,
/* Too young to die */
if (!timeout || 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;
}
@@ -327,10 +321,19 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
if (ino->flags & AUTOFS_INF_PENDING)
goto out;
if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
- ino->flags |= AUTOFS_INF_EXPIRING;
- init_completion(&ino->expire_complete);
+ ino->flags |= AUTOFS_INF_NO_RCU;
spin_unlock(&sbi->fs_lock);
- return root;
+ synchronize_rcu();
+ spin_lock(&sbi->fs_lock);
+ if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
+ ino->flags |= AUTOFS_INF_EXPIRING;
+ smp_mb();
+ ino->flags &= ~AUTOFS_INF_NO_RCU;
+ init_completion(&ino->expire_complete);
+ spin_unlock(&sbi->fs_lock);
+ return root;
+ }
+ ino->flags &= ~AUTOFS_INF_NO_RCU;
}
out:
spin_unlock(&sbi->fs_lock);
@@ -339,6 +342,89 @@ 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 expired;
+ }
+ }
+ return NULL;
+}
/*
* Find an eligible tree to time-out
* A tree is eligible if :-
@@ -353,11 +439,8 @@ 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;
@@ -369,77 +452,28 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
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 (ino->flags & AUTOFS_INF_NO_RCU)
+ expired = NULL;
+ else
+ expired = should_expire(dentry, mnt, timeout, how);
+ if (!expired) {
+ spin_unlock(&sbi->fs_lock);
+ continue;
}
-
- 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) {
+ ino = autofs4_dentry_ino(expired);
+ ino->flags |= AUTOFS_INF_NO_RCU;
+ spin_unlock(&sbi->fs_lock);
+ synchronize_rcu();
+ spin_lock(&sbi->fs_lock);
+ if (should_expire(expired, mnt, timeout, how)) {
+ if (expired != dentry)
dput(dentry);
- goto found;
- }
+ goto found;
}
-next:
+
+ ino->flags &= ~AUTOFS_INF_NO_RCU;
+ if (expired != dentry)
+ dput(expired);
spin_unlock(&sbi->fs_lock);
}
return NULL;
@@ -447,8 +481,9 @@ next:
found:
DPRINTK("returning %p %.*s",
expired, (int)expired->d_name.len, expired->d_name.name);
- ino = autofs4_dentry_ino(expired);
ino->flags |= AUTOFS_INF_EXPIRING;
+ smp_mb();
+ ino->flags &= ~AUTOFS_INF_NO_RCU;
init_completion(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
spin_lock(&sbi->lookup_lock);
@@ -461,13 +496,18 @@ found:
return expired;
}
-int autofs4_expire_wait(struct dentry *dentry)
+int autofs4_expire_wait(struct dentry *dentry, int rcu_walk)
{
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
int status;
/* Block on any pending expire */
+ if (!(ino->flags & (AUTOFS_INF_EXPIRING | AUTOFS_INF_NO_RCU)))
+ return 0;
+ if (rcu_walk)
+ return -ECHILD;
+
spin_lock(&sbi->fs_lock);
if (ino->flags & AUTOFS_INF_EXPIRING) {
spin_unlock(&sbi->fs_lock);
@@ -519,6 +559,8 @@ int autofs4_expire_run(struct super_block *sb,
spin_lock(&sbi->fs_lock);
ino = autofs4_dentry_ino(dentry);
+ /* avoid rapid-fire expire attempts if expiry fails */
+ ino->last_used = now;
ino->flags &= ~AUTOFS_INF_EXPIRING;
complete_all(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
@@ -545,6 +587,8 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
spin_lock(&sbi->fs_lock);
+ /* avoid rapid-fire expire attempts if expiry fails */
+ ino->last_used = now;
ino->flags &= ~AUTOFS_INF_EXPIRING;
complete_all(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-02 01:27:57 +0300