[PATCH 3.16 019/245] btrfs: new define for the inline extent data start

Ben Hutchings
2020-04-23T23:25:35Z

From: David Sterba <dsterba@suse.cz>

commit 7ec20afbcb7b257aec82ea5d66e6b0b7499abaca upstream.

Use a common definition for the inline data start so we don't have to
open-code it and introduce bugs like "Btrfs: fix wrong max inline data
size limit" fixed.

Signed-off-by: David Sterba <dsterba@suse.cz>
[bwh: Backported to 3.16 as dependency of various fixes: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/btrfs/ctree.c | 3 +--
fs/btrfs/ctree.h | 16 ++++++++--------
2 files changed, 9 insertions(+), 10 deletions(-)

--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -4609,8 +4609,7 @@ void btrfs_truncate_item(struct btrfs_ro
ptr = btrfs_item_ptr_offset(leaf, slot);
memmove_extent_buffer(leaf, ptr,
(unsigned long)fi,
- offsetof(struct btrfs_file_extent_item,
- disk_bytenr));
+ BTRFS_FILE_EXTENT_INLINE_DATA_START);
}
}

--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -392,9 +392,11 @@ struct btrfs_header {
sizeof(struct btrfs_key_ptr))
#define __BTRFS_LEAF_DATA_SIZE(bs) ((bs) - sizeof(struct btrfs_header))
#define BTRFS_LEAF_DATA_SIZE(r) (__BTRFS_LEAF_DATA_SIZE(r->leafsize))
+#define BTRFS_FILE_EXTENT_INLINE_DATA_START \
+ (offsetof(struct btrfs_file_extent_item, disk_bytenr))
#define BTRFS_MAX_INLINE_DATA_SIZE(r) (BTRFS_LEAF_DATA_SIZE(r) - \
sizeof(struct btrfs_item) - \
- offsetof(struct btrfs_file_extent_item, disk_bytenr))
+ BTRFS_FILE_EXTENT_INLINE_DATA_START)
#define BTRFS_MAX_XATTR_SIZE(r) (BTRFS_LEAF_DATA_SIZE(r) - \
sizeof(struct btrfs_item) -\
sizeof(struct btrfs_dir_item))
@@ -904,6 +906,8 @@ struct btrfs_file_extent_item {
/*
* disk space consumed by the extent, checksum blocks are included
* in these numbers
+ *
+ * At this offset in the structure, the inline extent data start.
*/
__le64 disk_bytenr;
__le64 disk_num_bytes;
@@ -3050,14 +3054,12 @@ BTRFS_SETGET_STACK_FUNCS(stack_file_exte
static inline unsigned long
btrfs_file_extent_inline_start(struct btrfs_file_extent_item *e)
{
- unsigned long offset = (unsigned long)e;
- offset += offsetof(struct btrfs_file_extent_item, disk_bytenr);
- return offset;
+ return (unsigned long)e + BTRFS_FILE_EXTENT_INLINE_DATA_START;
}

static inline u32 btrfs_file_extent_calc_inline_size(u32 datasize)
{
- return offsetof(struct btrfs_file_extent_item, disk_bytenr) + datasize;
+ return BTRFS_FILE_EXTENT_INLINE_DATA_START + datasize;
}

BTRFS_SETGET_FUNCS(file_extent_disk_bytenr, struct btrfs_file_extent_item,
@@ -3087,9 +3089,7 @@ BTRFS_SETGET_FUNCS(file_extent_other_enc
static inline u32 btrfs_file_extent_inline_item_len(struct extent_buffer *eb,
struct btrfs_item *e)
{
- unsigned long offset;
- offset = offsetof(struct btrfs_file_extent_item, disk_bytenr);
- return btrfs_item_size(eb, e) - offset;
+ return btrfs_item_size(eb, e) - BTRFS_FILE_EXTENT_INLINE_DATA_START;
}

/* this returns the number of file bytes represented by the inline item.