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Date: Mon, 15 Oct 2012 12:14:37 -0700
From: Anatol Pomozov <anatol.pomozov@...il.com>
To: tytso@....edu, wenqing.lz@...bao.com, linux-ext4@...r.kernel.org
Cc: Anatol Pomozov <anatol.pomozov@...il.com>
Subject: Re: [PATCH 2/2] ext4: Remove code duplication in ext4_get_block_write_nolock()
On Mon, Oct 15, 2012 at 12:06 PM, Anatol Pomozov
<anatol.pomozov@...il.com> wrote:
> 729f52c6be51013 introduced function ext4_get_block_write_nolock() that
> is very similar to _ext4_get_block(). Eliminate code duplication
> by passing different flags to _ext4_get_block()
>
> Tested: xfs tests
>
> Signed-off-by: Anatol Pomozov <anatol.pomozov@...il.com>
> ---
> fs/ext4/inode.c | 63 ++++++++++++++++++++++-----------------------------------
> 1 file changed, 24 insertions(+), 39 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index b3c243b..9829c3d 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -683,7 +683,7 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,
> map.m_lblk = iblock;
> map.m_len = bh->b_size >> inode->i_blkbits;
>
> - if (flags && !handle) {
> + if (flags && !(flags | EXT4_GET_BLOCKS_NO_LOCK) && !handle) {
> /* Direct IO write... */
> if (map.m_len > DIO_MAX_BLOCKS)
> map.m_len = DIO_MAX_BLOCKS;
> @@ -880,6 +880,8 @@ static int do_journal_get_write_access(handle_t *handle,
>
> static int ext4_get_block_write(struct inode *inode, sector_t iblock,
> struct buffer_head *bh_result, int create);
> +static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock,
> + struct buffer_head *bh_result, int create);
> static int ext4_write_begin(struct file *file, struct address_space *mapping,
> loff_t pos, unsigned len, unsigned flags,
> struct page **pagep, void **fsdata)
> @@ -2850,29 +2852,12 @@ static int ext4_get_block_write(struct inode *inode, sector_t iblock,
> }
>
> static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock,
> - struct buffer_head *bh_result, int flags)
> + struct buffer_head *bh_result, int create)
> {
> - handle_t *handle = ext4_journal_current_handle();
> - struct ext4_map_blocks map;
> - int ret = 0;
> -
> - ext4_debug("ext4_get_block_write_nolock: inode %lu, flag %d\n",
> - inode->i_ino, flags);
> -
> - flags = EXT4_GET_BLOCKS_NO_LOCK;
> -
> - map.m_lblk = iblock;
> - map.m_len = bh_result->b_size >> inode->i_blkbits;
> -
> - ret = ext4_map_blocks(handle, inode, &map, flags);
> - if (ret > 0) {
> - map_bh(bh_result, inode->i_sb, map.m_pblk);
> - bh_result->b_state = (bh_result->b_state & ~EXT4_MAP_FLAGS) |
> - map.m_flags;
> - bh_result->b_size = inode->i_sb->s_blocksize * map.m_len;
> - ret = 0;
> - }
> - return ret;
> + ext4_debug("ext4_get_block_write_nolock: inode %lu, create flag %d\n",
> + inode->i_ino, create);
> + return _ext4_get_block(inode, iblock, bh_result,
> + EXT4_GET_BLOCKS_NO_LOCK);
> }
>
> static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
> @@ -3003,6 +2988,8 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
> loff_t final_size = offset + count;
> if (rw == WRITE && final_size <= inode->i_size) {
> int overwrite = 0;
> + get_block_t *get_block_func = NULL;
> + int dio_flags = 0;
>
> BUG_ON(iocb->private == NULL);
>
> @@ -3056,22 +3043,20 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
> ext4_inode_aio_set(inode, io_end);
> }
>
> - if (overwrite)
> - ret = __blockdev_direct_IO(rw, iocb, inode,
> - inode->i_sb->s_bdev, iov,
> - offset, nr_segs,
> - ext4_get_block_write_nolock,
> - ext4_end_io_dio,
> - NULL,
> - 0);
> - else
> - ret = __blockdev_direct_IO(rw, iocb, inode,
> - inode->i_sb->s_bdev, iov,
> - offset, nr_segs,
> - ext4_get_block_write,
> - ext4_end_io_dio,
> - NULL,
> - DIO_LOCKING);
> + if (overwrite) {
> + get_block_func = ext4_get_block_write_nolock;
Ideally if block layer (function __blockdev_direct_IO) accepted some
user-data (e.g. flag) and later passed it back to callback function
(i.e. ext4_get_block_write). In this case we do not need two functions
ext4_get_block_write/ext4_get_block_write_nolock.
> + } else {
> + get_block_func = ext4_get_block_write;
> + dio_flags = DIO_LOCKING;
> + }
> + ret = __blockdev_direct_IO(rw, iocb, inode,
> + inode->i_sb->s_bdev, iov,
> + offset, nr_segs,
> + get_block_func,
> + ext4_end_io_dio,
> + NULL,
> + dio_flags);
> +
> if (iocb->private)
> ext4_inode_aio_set(inode, NULL);
> /*
> --
> 1.8.0.rc1
>
--
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