ext4: add a new ioctl EXT4_IOC_CLEAR_ES_CACHE

The new ioctl EXT4_IOC_CLEAR_ES_CACHE will force an inode's extent
status cache to be cleared out.  This is intended for use for
debugging.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index bf660aa..b22f24f 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -649,6 +649,8 @@ enum {
 #define EXT4_IOC_SET_ENCRYPTION_POLICY FS_IOC_SET_ENCRYPTION_POLICY
 #define EXT4_IOC_GET_ENCRYPTION_PWSALT FS_IOC_GET_ENCRYPTION_PWSALT
 #define EXT4_IOC_GET_ENCRYPTION_POLICY FS_IOC_GET_ENCRYPTION_POLICY
+/* ioctl codes 19--39 are reserved for fscrypt */
+#define EXT4_IOC_CLEAR_ES_CACHE                _IO('f', 40)
 
 #define EXT4_IOC_FSGETXATTR            FS_IOC_FSGETXATTR
 #define EXT4_IOC_FSSETXATTR            FS_IOC_FSSETXATTR

diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index 7521de2..02cc8eb 100644 (file)
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -1374,6 +1374,34 @@ static int es_reclaim_extents(struct ext4_inode_info *ei, int *nr_to_scan)
        return nr_shrunk;
 }
 
+/*
+ * Called to support EXT4_IOC_CLEAR_ES_CACHE.  We can only remove
+ * discretionary entries from the extent status cache.  (Some entries
+ * must be present for proper operations.)
+ */
+void ext4_clear_inode_es(struct inode *inode)
+{
+       struct ext4_inode_info *ei = EXT4_I(inode);
+       struct extent_status *es;
+       struct ext4_es_tree *tree;
+       struct rb_node *node;
+
+       write_lock(&ei->i_es_lock);
+       tree = &EXT4_I(inode)->i_es_tree;
+       tree->cache_es = NULL;
+       node = rb_first(&tree->root);
+       while (node) {
+               es = rb_entry(node, struct extent_status, rb_node);
+               node = rb_next(node);
+               if (!ext4_es_is_delayed(es)) {
+                       rb_erase(&es->rb_node, &tree->root);
+                       ext4_es_free_extent(inode, es);
+               }
+       }
+       ext4_clear_inode_state(inode, EXT4_STATE_EXT_PRECACHED);
+       write_unlock(&ei->i_es_lock);
+}
+
 #ifdef ES_DEBUG__
 static void ext4_print_pending_tree(struct inode *inode)
 {

diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h
index 131a8b7..e16785f 100644 (file)
--- a/fs/ext4/extents_status.h
+++ b/fs/ext4/extents_status.h
@@ -248,5 +248,6 @@ extern unsigned int ext4_es_delayed_clu(struct inode *inode, ext4_lblk_t lblk,
                                        ext4_lblk_t len);
 extern void ext4_es_remove_blks(struct inode *inode, ext4_lblk_t lblk,
                                ext4_lblk_t len);
+extern void ext4_clear_inode_es(struct inode *inode);
 
 #endif /* _EXT4_EXTENTS_STATUS_H */

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 442f7ef..15b1047 100644 (file)
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -1115,6 +1115,14 @@ resizefs_out:
        case EXT4_IOC_GET_ENCRYPTION_POLICY:
                return fscrypt_ioctl_get_policy(filp, (void __user *)arg);
 
+       case EXT4_IOC_CLEAR_ES_CACHE:
+       {
+               if (!inode_owner_or_capable(inode))
+                       return -EACCES;
+               ext4_clear_inode_es(inode);
+               return 0;
+       }
+
        case EXT4_IOC_FSGETXATTR:
        {
                struct fsxattr fa;
@@ -1233,6 +1241,7 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
        case EXT4_IOC_GET_ENCRYPTION_POLICY:
        case EXT4_IOC_SHUTDOWN:
        case FS_IOC_GETFSMAP:
+       case EXT4_IOC_CLEAR_ES_CACHE:
                break;
        default:
                return -ENOIOCTLCMD;