ext4: Add support FALLOC_FL_COLLAPSE_RANGE for fallocate

This patch implements fallocate's FALLOC_FL_COLLAPSE_RANGE for Ext4.
 
The semantics of this flag are following:
1) It collapses the range lying between offset and length by removing any data
   blocks which are present in this range and than updates all the logical
   offsets of extents beyond "offset + len" to nullify the hole created by
   removing blocks. In short, it does not leave a hole.
2) It should be used exclusively. No other fallocate flag in combination.
3) Offset and length supplied to fallocate should be fs block size aligned
   in case of xfs and ext4.
4) Collaspe range does not work beyond i_size.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
Tested-by: Dongsu Park <dongsu.park@profitbricks.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 32 insertions, 1 deletions

diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 451e0202aa69..e9d7ee77d3a1 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -16,6 +16,11 @@ struct mpage_da_data;
 struct ext4_map_blocks;
 struct extent_status;
 
+/* shim until we merge in the xfs_collapse_range branch */
+#ifndef FALLOC_FL_COLLAPSE_RANGE
+#define FALLOC_FL_COLLAPSE_RANGE        0x08
+#endif
+
 #define EXT4_I(inode) (container_of(inode, struct ext4_inode_info, vfs_inode))
 
 #define show_mballoc_flags(flags) __print_flags(flags, "|",     \
@@ -71,7 +76,8 @@ struct extent_status;
 #define show_falloc_mode(mode) __print_flags(mode, "|",         \
         { FALLOC_FL_KEEP_SIZE,          "KEEP_SIZE"},           \
         { FALLOC_FL_PUNCH_HOLE,         "PUNCH_HOLE"},          \
-        { FALLOC_FL_NO_HIDE_STALE,      "NO_HIDE_STALE"})
+        { FALLOC_FL_NO_HIDE_STALE,      "NO_HIDE_STALE"},       \
+        { FALLOC_FL_COLLAPSE_RANGE,     "COLLAPSE_RANGE"})
 
 
 TRACE_EVENT(ext4_free_inode,
@@ -2415,6 +2421,31 @@ TRACE_EVENT(ext4_es_shrink_exit,
                   __entry->shrunk_nr, __entry->cache_cnt)
 );
 
+TRACE_EVENT(ext4_collapse_range,
+        TP_PROTO(struct inode *inode, loff_t offset, loff_t len),
+
+        TP_ARGS(inode, offset, len),
+
+        TP_STRUCT__entry(
+                __field(dev_t,  dev)
+                __field(ino_t,  ino)
+                __field(loff_t, offset)
+                __field(loff_t, len)
+        ),
+
+        TP_fast_assign(
+                __entry->dev    = inode->i_sb->s_dev;
+                __entry->ino    = inode->i_ino;
+                __entry->offset = offset;
+                __entry->len    = len;
+        ),
+
+        TP_printk("dev %d,%d ino %lu offset %lld len %lld",
+                  MAJOR(__entry->dev), MINOR(__entry->dev),
+                  (unsigned long) __entry->ino,
+                  __entry->offset, __entry->len)
+);
+
 #endif /* _TRACE_EXT4_H */
 
 /* This part must be outside protection */