ext4: add new ioctl EXT4_IOC_GET_ES_CACHE

For debugging reasons, it's useful to know the contents of the extent
cache.  Since the extent cache contains much of what is in the fiemap
ioctl, use an fiemap-style interface to return this information.

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

1 files changed, 10 insertions, 0 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ee296797bcd2..e2d8ad27f4d1 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -652,6 +652,7 @@ enum {
 /* ioctl codes 19--39 are reserved for fscrypt */
 #define EXT4_IOC_CLEAR_ES_CACHE         _IO('f', 40)
 #define EXT4_IOC_GETSTATE               _IOW('f', 41, __u32)
+#define EXT4_IOC_GET_ES_CACHE           _IOWR('f', 42, struct fiemap)
 
 #define EXT4_IOC_FSGETXATTR             FS_IOC_FSGETXATTR
 #define EXT4_IOC_FSSETXATTR             FS_IOC_FSSETXATTR
@@ -692,6 +693,12 @@ enum {
 #define EXT4_IOC32_SETVERSION_OLD       FS_IOC32_SETVERSION
 #endif
 
+/*
+ * Returned by EXT4_IOC_GET_ES_CACHE as an additional possible flag.
+ * It indicates that the entry in extent status cache is for a hole.
+ */
+#define EXT4_FIEMAP_EXTENT_HOLE         0x08000000
+
 /* Max physical block we can address w/o extents */
 #define EXT4_MAX_BLOCK_FILE_PHYS        0xFFFFFFFF
 
@@ -3258,6 +3265,9 @@ extern int ext4_ext_check_inode(struct inode *inode);
 extern ext4_lblk_t ext4_ext_next_allocated_block(struct ext4_ext_path *path);
 extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                         __u64 start, __u64 len);
+extern int ext4_get_es_cache(struct inode *inode,
+                             struct fiemap_extent_info *fieinfo,
+                             __u64 start, __u64 len);
 extern int ext4_ext_precache(struct inode *inode);
 extern int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len);
 extern int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len);