Add an API so that client programs can discover a reasonable maximum
extent tree depth. This will eventually be used by e2fsck as one of
the criteria to decide if an extent-based file should have its extent
tree rebuilt.
Turn some related magic numbers into constants while we're at it.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
lib/ext2fs/ext2fs.h | 1 +
lib/ext2fs/ext3_extents.h | 2 ++
lib/ext2fs/extent.c | 33 +++++++++++++++++++++++++++++----
3 files changed, 32 insertions(+), 4 deletions(-)
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index afe4fd5..c3142f7 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -1218,6 +1218,7 @@ extern errcode_t ext2fs_extent_goto(ext2_extent_handle_t handle,
extern errcode_t ext2fs_extent_goto2(ext2_extent_handle_t handle,
int leaf_level, blk64_t blk);
extern errcode_t ext2fs_extent_fix_parents(ext2_extent_handle_t handle);
+size_t ext2fs_max_extent_depth(ext2_extent_handle_t handle);
/* fileio.c */
extern errcode_t ext2fs_file_open2(ext2_filsys fs, ext2_ino_t ino,
diff --git a/lib/ext2fs/ext3_extents.h b/lib/ext2fs/ext3_extents.h
index 66c23fd..f73a332 100644
--- a/lib/ext2fs/ext3_extents.h
+++ b/lib/ext2fs/ext3_extents.h
@@ -98,6 +98,8 @@ struct ext3_ext_path {
*/
#define EXT_INIT_MAX_LEN (1UL << 15)
#define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1)
+#define EXT_MAX_EXTENT_LBLK (((__u64) 1 << 32) - 1)
+#define EXT_MAX_EXTENT_PBLK (((__u64) 1 << 48) - 1)
#define EXT_FIRST_EXTENT(__hdr__) \
((struct ext3_extent *) (((char *) (__hdr__)) + \
diff --git a/lib/ext2fs/extent.c b/lib/ext2fs/extent.c
index afb79c8..b1130f6 100644
--- a/lib/ext2fs/extent.c
+++ b/lib/ext2fs/extent.c
@@ -1697,14 +1697,39 @@ errcode_t ext2fs_extent_get_info(ext2_extent_handle_t handle,
info->curr_level = handle->level;
info->max_depth = handle->max_depth;
- info->max_lblk = ((__u64) 1 << 32) - 1;
- info->max_pblk = ((__u64) 1 << 48) - 1;
- info->max_len = (1UL << 15);
- info->max_uninit_len = (1UL << 15) - 1;
+ info->max_lblk = EXT_MAX_EXTENT_LBLK;
+ info->max_pblk = EXT_MAX_EXTENT_PBLK;
+ info->max_len = EXT_INIT_MAX_LEN;
+ info->max_uninit_len = EXT_UNINIT_MAX_LEN;
return 0;
}
+static int ul_log2(unsigned long arg)
+{
+ int l = 0;
+
+ arg >>= 1;
+ while (arg) {
+ l++;
+ arg >>= 1;
+ }
+ return l;
+}
+
+size_t ext2fs_max_extent_depth(ext2_extent_handle_t handle)
+{
+ size_t iblock_sz = sizeof(((struct ext2_inode *)NULL)->i_block);
+ size_t iblock_extents = (iblock_sz - sizeof(struct ext3_extent_header)) /
+ sizeof(struct ext3_extent);
+ size_t extents_per_block = (handle->fs->blocksize -
+ sizeof(struct ext3_extent_header)) /
+ sizeof(struct ext3_extent);
+
+ return 1 + ((ul_log2(EXT_MAX_EXTENT_LBLK) - ul_log2(iblock_extents)) /
+ ul_log2(extents_per_block));
+}
+
#ifdef DEBUG
/*
* Override debugfs's prompt
--
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