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-rw-r--r--fs/autofs/dirhash.c249
1 files changed, 249 insertions, 0 deletions
diff --git a/fs/autofs/dirhash.c b/fs/autofs/dirhash.c
new file mode 100644
index 0000000..448143f
--- /dev/null
+++ b/fs/autofs/dirhash.c
@@ -0,0 +1,249 @@
+/* -*- linux-c -*- --------------------------------------------------------- *
+ *
+ * linux/fs/autofs/dirhash.c
+ *
+ * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
+ *
+ * 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"
+
+/* Functions for maintenance of expiry queue */
+
+static void autofs_init_usage(struct autofs_dirhash *dh,
+ struct autofs_dir_ent *ent)
+{
+ list_add_tail(&ent->exp, &dh->expiry_head);
+ ent->last_usage = jiffies;
+}
+
+static void autofs_delete_usage(struct autofs_dir_ent *ent)
+{
+ list_del(&ent->exp);
+}
+
+void autofs_update_usage(struct autofs_dirhash *dh,
+ struct autofs_dir_ent *ent)
+{
+ autofs_delete_usage(ent); /* Unlink from current position */
+ autofs_init_usage(dh,ent); /* Relink at queue tail */
+}
+
+struct autofs_dir_ent *autofs_expire(struct super_block *sb,
+ struct autofs_sb_info *sbi,
+ struct vfsmount *mnt)
+{
+ struct autofs_dirhash *dh = &sbi->dirhash;
+ struct autofs_dir_ent *ent;
+ struct dentry *dentry;
+ unsigned long timeout = sbi->exp_timeout;
+
+ while (1) {
+ if ( list_empty(&dh->expiry_head) || sbi->catatonic )
+ return NULL; /* No entries */
+ /* We keep the list sorted by last_usage and want old stuff */
+ ent = list_entry(dh->expiry_head.next, struct autofs_dir_ent, exp);
+ if (jiffies - ent->last_usage < timeout)
+ break;
+ /* Move to end of list in case expiry isn't desirable */
+ autofs_update_usage(dh, ent);
+
+ /* Check to see that entry is expirable */
+ if ( ent->ino < AUTOFS_FIRST_DIR_INO )
+ return ent; /* Symlinks are always expirable */
+
+ /* Get the dentry for the autofs subdirectory */
+ dentry = ent->dentry;
+
+ if ( !dentry ) {
+ /* Should only happen in catatonic mode */
+ printk("autofs: dentry == NULL but inode range is directory, entry %s\n", ent->name);
+ autofs_delete_usage(ent);
+ continue;
+ }
+
+ if ( !dentry->d_inode ) {
+ dput(dentry);
+ printk("autofs: negative dentry on expiry queue: %s\n",
+ ent->name);
+ autofs_delete_usage(ent);
+ continue;
+ }
+
+ /* Make sure entry is mounted and unused; note that dentry will
+ point to the mounted-on-top root. */
+ if (!S_ISDIR(dentry->d_inode->i_mode)||!d_mountpoint(dentry)) {
+ DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
+ continue;
+ }
+ mntget(mnt);
+ dget(dentry);
+ if (!follow_down(&mnt, &dentry)) {
+ dput(dentry);
+ mntput(mnt);
+ DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
+ continue;
+ }
+ while (d_mountpoint(dentry) && follow_down(&mnt, &dentry))
+ ;
+ dput(dentry);
+
+ if ( may_umount(mnt) == 0 ) {
+ mntput(mnt);
+ DPRINTK(("autofs: signaling expire on %s\n", ent->name));
+ return ent; /* Expirable! */
+ }
+ DPRINTK(("autofs: didn't expire due to may_umount: %s\n", ent->name));
+ mntput(mnt);
+ }
+ return NULL; /* No expirable entries */
+}
+
+void autofs_initialize_hash(struct autofs_dirhash *dh) {
+ memset(&dh->h, 0, AUTOFS_HASH_SIZE*sizeof(struct autofs_dir_ent *));
+ INIT_LIST_HEAD(&dh->expiry_head);
+}
+
+struct autofs_dir_ent *autofs_hash_lookup(const struct autofs_dirhash *dh, struct qstr *name)
+{
+ struct autofs_dir_ent *dhn;
+
+ DPRINTK(("autofs_hash_lookup: hash = 0x%08x, name = ", name->hash));
+ autofs_say(name->name,name->len);
+
+ for ( dhn = dh->h[(unsigned) name->hash % AUTOFS_HASH_SIZE] ; dhn ; dhn = dhn->next ) {
+ if ( name->hash == dhn->hash &&
+ name->len == dhn->len &&
+ !memcmp(name->name, dhn->name, name->len) )
+ break;
+ }
+
+ return dhn;
+}
+
+void autofs_hash_insert(struct autofs_dirhash *dh, struct autofs_dir_ent *ent)
+{
+ struct autofs_dir_ent **dhnp;
+
+ DPRINTK(("autofs_hash_insert: hash = 0x%08x, name = ", ent->hash));
+ autofs_say(ent->name,ent->len);
+
+ autofs_init_usage(dh,ent);
+ if (ent->dentry)
+ dget(ent->dentry);
+
+ dhnp = &dh->h[(unsigned) ent->hash % AUTOFS_HASH_SIZE];
+ ent->next = *dhnp;
+ ent->back = dhnp;
+ *dhnp = ent;
+ if ( ent->next )
+ ent->next->back = &(ent->next);
+}
+
+void autofs_hash_delete(struct autofs_dir_ent *ent)
+{
+ *(ent->back) = ent->next;
+ if ( ent->next )
+ ent->next->back = ent->back;
+
+ autofs_delete_usage(ent);
+
+ if ( ent->dentry )
+ dput(ent->dentry);
+ kfree(ent->name);
+ kfree(ent);
+}
+
+/*
+ * Used by readdir(). We must validate "ptr", so we can't simply make it
+ * a pointer. Values below 0xffff are reserved; calling with any value
+ * <= 0x10000 will return the first entry found.
+ *
+ * "last" can be NULL or the value returned by the last search *if* we
+ * want the next sequential entry.
+ */
+struct autofs_dir_ent *autofs_hash_enum(const struct autofs_dirhash *dh,
+ off_t *ptr, struct autofs_dir_ent *last)
+{
+ int bucket, ecount, i;
+ struct autofs_dir_ent *ent;
+
+ bucket = (*ptr >> 16) - 1;
+ ecount = *ptr & 0xffff;
+
+ if ( bucket < 0 ) {
+ bucket = ecount = 0;
+ }
+
+ DPRINTK(("autofs_hash_enum: bucket %d, entry %d\n", bucket, ecount));
+
+ ent = last ? last->next : NULL;
+
+ if ( ent ) {
+ ecount++;
+ } else {
+ while ( bucket < AUTOFS_HASH_SIZE ) {
+ ent = dh->h[bucket];
+ for ( i = ecount ; ent && i ; i-- )
+ ent = ent->next;
+
+ if (ent) {
+ ecount++; /* Point to *next* entry */
+ break;
+ }
+
+ bucket++; ecount = 0;
+ }
+ }
+
+#ifdef DEBUG
+ if ( !ent )
+ printk("autofs_hash_enum: nothing found\n");
+ else {
+ printk("autofs_hash_enum: found hash %08x, name", ent->hash);
+ autofs_say(ent->name,ent->len);
+ }
+#endif
+
+ *ptr = ((bucket+1) << 16) + ecount;
+ return ent;
+}
+
+/* Iterate over all the ents, and remove all dentry pointers. Used on
+ entering catatonic mode, in order to make the filesystem unmountable. */
+void autofs_hash_dputall(struct autofs_dirhash *dh)
+{
+ int i;
+ struct autofs_dir_ent *ent;
+
+ for ( i = 0 ; i < AUTOFS_HASH_SIZE ; i++ ) {
+ for ( ent = dh->h[i] ; ent ; ent = ent->next ) {
+ if ( ent->dentry ) {
+ dput(ent->dentry);
+ ent->dentry = NULL;
+ }
+ }
+ }
+}
+
+/* Delete everything. This is used on filesystem destruction, so we
+ make no attempt to keep the pointers valid */
+void autofs_hash_nuke(struct autofs_dirhash *dh)
+{
+ int i;
+ struct autofs_dir_ent *ent, *nent;
+
+ for ( i = 0 ; i < AUTOFS_HASH_SIZE ; i++ ) {
+ for ( ent = dh->h[i] ; ent ; ent = nent ) {
+ nent = ent->next;
+ if ( ent->dentry )
+ dput(ent->dentry);
+ kfree(ent->name);
+ kfree(ent);
+ }
+ }
+}
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