On Tue, Aug 12, 2008 at 09:29:50AM -0700, Mingming Cao wrote:
>
......
....
>
> ===================================================================
> 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);
Why do we need to consider data=journaled mode here. We are not writing
any data here. Instead we are just inserting an extent.
> 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);
Even in data=journal mode directIO will put the buffer_heads to journal
right ? . So should we use ext4_data_trans_blocks here ?
> 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
>
> /*
>
....
....
-aneesh
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