From 729f52c6be51013c9268e5fc85acbc1091286fdb Mon Sep 17 00:00:00 2001 From: Zheng Liu Date: Mon, 9 Jul 2012 16:29:29 -0400 Subject: [PATCH] ext4: add a new nolock flag in ext4_map_blocks EXT4_GET_BLOCKS_NO_LOCK flag is added to indicate that we don't need to acquire i_data_sem lock in ext4_map_blocks. Meanwhile, it changes ext4_get_block() to not start a new journal because when we do a overwrite dio, there is no any metadata that needs to be modified. We define a new function called ext4_get_block_write_nolock, which is used in dio overwrite nolock. In this function, it doesn't try to acquire i_data_sem lock and doesn't start a new journal as it does a lookup. CC: Tao Ma CC: Eric Sandeen CC: Robin Dong Signed-off-by: Zheng Liu Signed-off-by: "Theodore Ts'o" --- fs/ext4/ext4.h | 2 ++ fs/ext4/inode.c | 59 ++++++++++++++++++++++++++++++++++++++++--------- 2 files changed, 51 insertions(+), 10 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 01434f25917d..4a49f8225d0b 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -571,6 +571,8 @@ enum { #define EXT4_GET_BLOCKS_NO_NORMALIZE 0x0040 /* Request will not result in inode size update (user for fallocate) */ #define EXT4_GET_BLOCKS_KEEP_SIZE 0x0080 + /* Do not take i_data_sem locking in ext4_map_blocks */ +#define EXT4_GET_BLOCKS_NO_LOCK 0x0100 /* * Flags used by ext4_free_blocks diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 02bc8cbe7281..76cb3b1ad78a 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -544,7 +544,8 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode, * Try to see if we can get the block without requesting a new * file system block. */ - down_read((&EXT4_I(inode)->i_data_sem)); + if (!(flags & EXT4_GET_BLOCKS_NO_LOCK)) + down_read((&EXT4_I(inode)->i_data_sem)); if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) { retval = ext4_ext_map_blocks(handle, inode, map, flags & EXT4_GET_BLOCKS_KEEP_SIZE); @@ -552,7 +553,8 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode, retval = ext4_ind_map_blocks(handle, inode, map, flags & EXT4_GET_BLOCKS_KEEP_SIZE); } - up_read((&EXT4_I(inode)->i_data_sem)); + if (!(flags & EXT4_GET_BLOCKS_NO_LOCK)) + up_read((&EXT4_I(inode)->i_data_sem)); if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) { int ret = check_block_validity(inode, map); @@ -2818,6 +2820,32 @@ static int ext4_get_block_write(struct inode *inode, sector_t iblock, EXT4_GET_BLOCKS_IO_CREATE_EXT); } +static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock, + struct buffer_head *bh_result, int flags) +{ + 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; +} + static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset, ssize_t size, void *private, int ret, bool is_async) @@ -2966,6 +2994,8 @@ 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; + /* * We could direct write to holes and fallocate. * @@ -3005,13 +3035,22 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb, EXT4_I(inode)->cur_aio_dio = iocb->private; } - 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) + 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 (iocb->private) EXT4_I(inode)->cur_aio_dio = NULL; /* @@ -3031,7 +3070,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb, if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) { ext4_free_io_end(iocb->private); iocb->private = NULL; - } else if (ret > 0 && ext4_test_inode_state(inode, + } else if (ret > 0 && !overwrite && ext4_test_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN)) { int err; /* -- 2.20.1