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-rw-r--r--fs/btrfs/extent_map.c2
-rw-r--r--fs/btrfs/extent_map.h8
-rw-r--r--fs/btrfs/ioctl.c14
3 files changed, 24 insertions, 0 deletions
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 5a36add21305..c28ceddefae4 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -261,6 +261,7 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
em->mod_start = merge->mod_start;
em->generation = max(em->generation, merge->generation);
+ set_bit(EXTENT_FLAG_MERGED, &em->flags);
rb_erase_cached(&merge->rb_node, &tree->map);
RB_CLEAR_NODE(&merge->rb_node);
@@ -278,6 +279,7 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
RB_CLEAR_NODE(&merge->rb_node);
em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
em->generation = max(em->generation, merge->generation);
+ set_bit(EXTENT_FLAG_MERGED, &em->flags);
free_extent_map(merge);
}
}
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 8e217337dff9..d2fa32ffe304 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -25,6 +25,8 @@ enum {
EXTENT_FLAG_FILLING,
/* filesystem extent mapping type */
EXTENT_FLAG_FS_MAPPING,
+ /* This em is merged from two or more physically adjacent ems */
+ EXTENT_FLAG_MERGED,
};
struct extent_map {
@@ -40,6 +42,12 @@ struct extent_map {
u64 ram_bytes;
u64 block_start;
u64 block_len;
+
+ /*
+ * Generation of the extent map, for merged em it's the highest
+ * generation of all merged ems.
+ * For non-merged extents, it's from btrfs_file_extent_item::generation.
+ */
u64 generation;
unsigned long flags;
/* Used for chunk mappings, flag EXTENT_FLAG_FS_MAPPING must be set */
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index ffebd420829e..1398d7b64c4e 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1175,6 +1175,20 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
em = lookup_extent_mapping(em_tree, start, sectorsize);
read_unlock(&em_tree->lock);
+ /*
+ * We can get a merged extent, in that case, we need to re-search
+ * tree to get the original em for defrag.
+ *
+ * If @newer_than is 0 or em::generation < newer_than, we can trust
+ * this em, as either we don't care about the generation, or the
+ * merged extent map will be rejected anyway.
+ */
+ if (em && test_bit(EXTENT_FLAG_MERGED, &em->flags) &&
+ newer_than && em->generation >= newer_than) {
+ free_extent_map(em);
+ em = NULL;
+ }
+
if (!em) {
struct extent_state *cached = NULL;
u64 end = start + sectorsize - 1;