Change on-disk format to support 2^15 uninitialized extents
This change was suggested by Andreas Dilger.
This patch changes the EXT_MAX_LEN value and extent code which marks/checks
uninitialized extents. With this change it will be possible to have
initialized extents with 2^15 blocks (earlier the max blocks we could have
was 2^15 - 1). This way we can have better extent-to-block alignment.
Now, maximum number of blocks we can have in an initialized extent is 2^15
and in an uninitialized extent is 2^15 - 1.
Signed-off-by: Amit Arora <aarora@in.ibm.com>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ded3d46..77146b8 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1107,7 +1107,7 @@
ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
struct ext4_extent *ex2)
{
- unsigned short ext1_ee_len, ext2_ee_len;
+ unsigned short ext1_ee_len, ext2_ee_len, max_len;
/*
* Make sure that either both extents are uninitialized, or
@@ -1116,6 +1116,11 @@
if (ext4_ext_is_uninitialized(ex1) ^ ext4_ext_is_uninitialized(ex2))
return 0;
+ if (ext4_ext_is_uninitialized(ex1))
+ max_len = EXT_UNINIT_MAX_LEN;
+ else
+ max_len = EXT_INIT_MAX_LEN;
+
ext1_ee_len = ext4_ext_get_actual_len(ex1);
ext2_ee_len = ext4_ext_get_actual_len(ex2);
@@ -1128,7 +1133,7 @@
* as an RO_COMPAT feature, refuse to merge to extents if
* this can result in the top bit of ee_len being set.
*/
- if (ext1_ee_len + ext2_ee_len > EXT_MAX_LEN)
+ if (ext1_ee_len + ext2_ee_len > max_len)
return 0;
#ifdef AGGRESSIVE_TEST
if (le16_to_cpu(ex1->ee_len) >= 4)
@@ -1815,7 +1820,11 @@
ex->ee_block = cpu_to_le32(block);
ex->ee_len = cpu_to_le16(num);
- if (uninitialized)
+ /*
+ * Do not mark uninitialized if all the blocks in the
+ * extent have been removed.
+ */
+ if (uninitialized && num)
ext4_ext_mark_uninitialized(ex);
err = ext4_ext_dirty(handle, inode, path + depth);
@@ -2308,6 +2317,19 @@
/* allocate new block */
goal = ext4_ext_find_goal(inode, path, iblock);
+ /*
+ * See if request is beyond maximum number of blocks we can have in
+ * a single extent. For an initialized extent this limit is
+ * EXT_INIT_MAX_LEN and for an uninitialized extent this limit is
+ * EXT_UNINIT_MAX_LEN.
+ */
+ if (max_blocks > EXT_INIT_MAX_LEN &&
+ create != EXT4_CREATE_UNINITIALIZED_EXT)
+ max_blocks = EXT_INIT_MAX_LEN;
+ else if (max_blocks > EXT_UNINIT_MAX_LEN &&
+ create == EXT4_CREATE_UNINITIALIZED_EXT)
+ max_blocks = EXT_UNINIT_MAX_LEN;
+
/* Check if we can really insert (iblock)::(iblock+max_blocks) extent */
newex.ee_block = cpu_to_le32(iblock);
newex.ee_len = cpu_to_le16(max_blocks);