The patch titled
ext4: uninitialised extent handling
has been added to the -mm tree. Its filename is
ext4-unitialized-extent-handling.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: ext4: uninitialised extent handling
From: Suparna Bhattacharya <suparna@xxxxxxxxxx>
Make it possible to add file preallocation support in future as an RO_COMPAT
feature by recognizing uninitialized extents as holes and limiting extent
length to keep the top bit of ee_len free for marking uninitialized extents.
Signed-off-by: Suparna Bhattacharya <suparna@xxxxxxxxxx>
Signed-off-by: Mingming Cao <cmm@xxxxxxxxxx>
Signed-off-by: Dave Kleikamp <shaggy@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/ext4/extents.c | 16 ++++++++++++++++
include/linux/ext4_fs_extents.h | 2 ++
2 files changed, 18 insertions(+)
diff -puN fs/ext4/extents.c~ext4-unitialized-extent-handling fs/ext4/extents.c
--- a/fs/ext4/extents.c~ext4-unitialized-extent-handling
+++ a/fs/ext4/extents.c
@@ -1082,6 +1082,13 @@ ext4_can_extents_be_merged(struct inode
!= le32_to_cpu(ex2->ee_block))
return 0;
+ /*
+ * To allow future support for preallocated extents to be added
+ * as an RO_COMPAT feature, refuse to merge to extents if
+ * can result in the top bit of ee_len being set
+ */
+ if (le16_to_cpu(ex1->ee_len) + le16_to_cpu(ex2->ee_len) > EXT_MAX_LEN)
+ return 0;
#ifdef AGRESSIVE_TEST
if (le16_to_cpu(ex1->ee_len) >= 4)
return 0;
@@ -1943,6 +1950,15 @@ int ext4_ext_get_blocks(handle_t *handle
unsigned long ee_block = le32_to_cpu(ex->ee_block);
ext4_fsblk_t ee_start = ext_pblock(ex);
unsigned short ee_len = le16_to_cpu(ex->ee_len);
+
+ /*
+ * Allow future support for preallocated extents to be added
+ * as an RO_COMPAT feature:
+ * Uninitialized extents are treated as holes, except that
+ * we avoid (fail) allocating new blocks during a write.
+ */
+ if (ee_len > EXT_MAX_LEN)
+ goto out2;
/* if found exent covers block, simple return it */
if (iblock >= ee_block && iblock < ee_block + ee_len) {
newblock = iblock - ee_block + ee_start;
diff -puN include/linux/ext4_fs_extents.h~ext4-unitialized-extent-handling include/linux/ext4_fs_extents.h
--- a/include/linux/ext4_fs_extents.h~ext4-unitialized-extent-handling
+++ a/include/linux/ext4_fs_extents.h
@@ -141,6 +141,8 @@ typedef int (*ext_prepare_callback)(stru
#define EXT_MAX_BLOCK 0xffffffff
+#define EXT_MAX_LEN ((1UL << 15) - 1)
+
#define EXT_FIRST_EXTENT(__hdr__) \
((struct ext4_extent *) (((char *) (__hdr__)) + \
_
Patches currently in -mm which might be from suparna@xxxxxxxxxx are
ext4-unitialized-extent-handling.patch
dio-centralize-completion-in-dio_complete.patch
dio-call-blk_run_address_space-once-per-op.patch
dio-formalize-bio-counters-as-a-dio-reference-count.patch
dio-remove-duplicate-bio-wait-code.patch
dio-only-call-aio_complete-after-returning-eiocbqueued.patch
-
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