Ext4: journal credits reservation fixes for DIO, fallocate
From: Mingming Cao <cmm@xxxxxxxxxx>
DIO and fallocate credit calculation is different than writepage, as
they do start a new journal right for each call to ext4_get_blocks_wrap().
This patch uses the helper function in DIO and fallocate case, passing
a flag indicating that the modified data are contiguous thus could account
less indirect/index blocks.
This patch also fixed the journal credit reservation for direct I/O
(DIO). Previously the estimated credits for DIO only was calculated for
non-extent files, which was not enough if the file is extent-based.
Also fixed was fallocate double-counting credits for modifying the the
superblock.
Signed-off-by: Mingming Cao <cmm@xxxxxxxxxx>
---
---
fs/ext4/ext4.h | 1 +
fs/ext4/extents.c | 7 +++----
fs/ext4/inode.c | 49 ++++++++++++++++++++++++++++---------------------
3 files changed, 32 insertions(+), 25 deletions(-)
===================================================================
Index: linux-2.6.27-rc1/fs/ext4/extents.c
===================================================================
--- linux-2.6.27-rc1.orig/fs/ext4/extents.c 2008-08-11 22:25:39.000000000 -0700
+++ linux-2.6.27-rc1/fs/ext4/extents.c 2008-08-11 22:25:55.000000000 -0700
@@ -2799,7 +2799,7 @@ void ext4_ext_truncate(struct inode *ino
/*
* probably first extent we're gonna free will be last in block
*/
- err = ext4_writepage_trans_blocks(inode) + 3;
+ err = ext4_writepage_trans_blocks(inode);
handle = ext4_journal_start(inode, err);
if (IS_ERR(handle))
return;
@@ -2951,10 +2951,9 @@ long ext4_fallocate(struct inode *inode,
max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
- block;
/*
- * credits to insert 1 extent into extent tree + buffers to be able to
- * modify 1 super block, 1 block bitmap and 1 group descriptor.
+ * credits to insert 1 extent into extent tree
*/
- credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + 3;
+ credits = ext4_data_trans_blocks(inode, max_blocks);
mutex_lock(&inode->i_mutex);
retry:
while (ret >= 0 && ret < max_blocks) {
Index: linux-2.6.27-rc1/fs/ext4/inode.c
===================================================================
--- linux-2.6.27-rc1.orig/fs/ext4/inode.c 2008-08-11 22:18:31.000000000 -0700
+++ linux-2.6.27-rc1/fs/ext4/inode.c 2008-08-11 22:25:55.000000000 -0700
@@ -1041,18 +1041,6 @@ static void ext4_da_update_reserve_space
spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
}
-/* Maximum number of blocks we map for direct IO at once. */
-#define DIO_MAX_BLOCKS 4096
-/*
- * Number of credits we need for writing DIO_MAX_BLOCKS:
- * We need sb + group descriptor + bitmap + inode -> 4
- * For B blocks with A block pointers per block we need:
- * 1 (triple ind.) + (B/A/A + 2) (doubly ind.) + (B/A + 2) (indirect).
- * If we plug in 4096 for B and 256 for A (for 1KB block size), we get 25.
- */
-#define DIO_CREDITS 25
-
-
/*
* The ext4_get_blocks_wrap() function try to look up the requested blocks,
* and returns if the blocks are already mapped.
@@ -1164,19 +1152,23 @@ int ext4_get_blocks_wrap(handle_t *handl
return retval;
}
+/* Maximum number of blocks we map for direct IO at once. */
+#define DIO_MAX_BLOCKS 4096
+
static int ext4_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
handle_t *handle = ext4_journal_current_handle();
int ret = 0, started = 0;
unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
+ int dio_credits;
if (create && !handle) {
/* Direct IO write... */
if (max_blocks > DIO_MAX_BLOCKS)
max_blocks = DIO_MAX_BLOCKS;
- handle = ext4_journal_start(inode, DIO_CREDITS +
- 2 * EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb));
+ dio_credits = ext4_data_trans_blocks(inode, max_blocks);
+ handle = ext4_journal_start(inode, dio_credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
goto out;
@@ -2222,7 +2214,7 @@ static int ext4_da_writepage(struct page
* for DIO, writepages, and truncate
*/
#define EXT4_MAX_WRITEBACK_PAGES DIO_MAX_BLOCKS
-#define EXT4_MAX_WRITEBACK_CREDITS DIO_CREDITS
+#define EXT4_MAX_WRITEBACK_CREDITS 25
static int ext4_da_writepages(struct address_space *mapping,
struct writeback_control *wbc)
@@ -4429,7 +4421,8 @@ static int ext4_writeblocks_trans_credit
/*
* Calulate the total number of credits to reserve to fit
- * the modification of a single pages into a single transaction
+ * the modification of a single pages into a single transaction,
+ * which may include multile chunk of block allocations.
*
* This could be called via ext4_write_begin() or later
* ext4_da_writepages() in delalyed allocation case.
@@ -4437,11 +4430,6 @@ static int ext4_writeblocks_trans_credit
* In both case it's possible that we could allocating multiple
* chunks of blocks. We need to consider the worse case, when
* one new block per extent.
- *
- * For Direct IO and fallocate, the journal credits reservation
- * is based on one single extent allocation, so they could use
- * EXT4_DATA_TRANS_BLOCKS to get the needed credit to log a single
- * chunk of allocation needs.
*/
int ext4_writepage_trans_blocks(struct inode *inode)
{
@@ -4451,6 +4439,25 @@ int ext4_writepage_trans_blocks(struct i
return ext4_writeblocks_trans_credits_old(inode, bpp, 0);
return ext4_ext_writepage_trans_blocks(inode, bpp, 0);
}
+
+/*
+ * Calculate the journal credits for a chunk of data modification.
+ *
+ * For Direct IO and fallocate, the journal credits reservation
+ * is based on one single extent allocation, so they could use
+ * this function to get the needed credit to log a single
+ * chunk of allocation needs.
+ *
+ * This is called from DIO, fallocate or whoever calling
+ * ext4_get_blocks_wrap() to map/allocate a chunk of contigous disk blocks
+ */
+int ext4_data_trans_blocks(struct inode *inode, int nrblocks)
+{
+ if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
+ return ext4_writeblocks_trans_credits_old(inode, nrblocks, 1);
+ return ext4_ext_writepage_trans_blocks(inode, nrblocks, 1);
+}
+
/*
* The caller must have previously called ext4_reserve_inode_write().
* Give this, we know that the caller already has write access to iloc->bh.
Index: linux-2.6.27-rc1/fs/ext4/ext4.h
===================================================================
--- linux-2.6.27-rc1.orig/fs/ext4/ext4.h 2008-08-11 22:18:31.000000000 -0700
+++ linux-2.6.27-rc1/fs/ext4/ext4.h 2008-08-11 22:25:55.000000000 -0700
@@ -1073,6 +1073,7 @@ extern void ext4_get_inode_flags(struct
extern void ext4_set_aops(struct inode *inode);
extern int ext4_writepage_trans_blocks(struct inode *);
extern int ext4_meta_trans_blocks(struct inode *, int nrblocks, int idxblocks);
+extern int ext4_data_trans_blocks(struct inode *, int nrblocks);
extern int ext4_block_truncate_page(handle_t *handle,
struct address_space *mapping, loff_t from);
extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page);
--
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