On Tue, Jun 9, 2015 at 1:04 PM, Liu Bo <bo.li.liu@xxxxxxxxxx> wrote:
> If we're overwriting an allocated file without changing timestamp
> and inode version, and the file is with NODATACOW, we don't have any metadata to
> commit, thus we can just flush the data device cache and go forward.
>
> However, if there's have any change on extents' disk bytenr, inode size,
> timestamp or inode version, we need to go through the normal btrfs_log_inode
> path.
>
> Test:
> ----------------------------
> 1. sysbench test of
> "1 file + 1 thread + bs=4k + size=40k + synchronous I/O mode + randomwrite +
> fsync_on_each_write",
> 2. loop device associated with tmpfs file
> 3.
> - For btrfs, "-o nodatacow" and "-o noi_version" option
> - For ext4 and xfs, no extra mount options
> ----------------------------
>
> Results:
> ----------------------------
> - btrfs:
> w/o: ~30Mb/sec
> w: ~181Mb/sec
>
> - other filesystems: (both don't enable i_version by default)
> ext4: 203Mb/sec
> xfs: 212Mb/sec
> ----------------------------
>
> Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
> ---
> fs/btrfs/btrfs_inode.h | 2 ++
> fs/btrfs/disk-io.c | 2 +-
> fs/btrfs/disk-io.h | 1 +
> fs/btrfs/file.c | 39 ++++++++++++++++++++++++++++++++++-----
> fs/btrfs/inode.c | 3 +++
> 5 files changed, 41 insertions(+), 6 deletions(-)
>
> diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
> index 0ef5cc1..b36d87a 100644
> --- a/fs/btrfs/btrfs_inode.h
> +++ b/fs/btrfs/btrfs_inode.h
> @@ -44,6 +44,8 @@
> #define BTRFS_INODE_IN_DELALLOC_LIST 9
> #define BTRFS_INODE_READDIO_NEED_LOCK 10
> #define BTRFS_INODE_HAS_PROPS 11
> +#define BTRFS_INODE_NOTIMESTAMP 12
> +#define BTRFS_INODE_NOISIZE 13
> /*
> * The following 3 bits are meant only for the btree inode.
> * When any of them is set, it means an error happened while writing an
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 2ef9a4b..de7fd94 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -3343,7 +3343,7 @@ static int write_dev_flush(struct btrfs_device *device, int wait)
> * send an empty flush down to each device in parallel,
> * then wait for them
> */
> -static int barrier_all_devices(struct btrfs_fs_info *info)
> +int barrier_all_devices(struct btrfs_fs_info *info)
> {
> struct list_head *head;
> struct btrfs_device *dev;
> diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
> index d4cbfee..2bc91fe 100644
> --- a/fs/btrfs/disk-io.h
> +++ b/fs/btrfs/disk-io.h
> @@ -60,6 +60,7 @@ void close_ctree(struct btrfs_root *root);
> int write_ctree_super(struct btrfs_trans_handle *trans,
> struct btrfs_root *root, int max_mirrors);
> struct buffer_head *btrfs_read_dev_super(struct block_device *bdev);
> +int barrier_all_devices(struct btrfs_fs_info *info);
> int btrfs_commit_super(struct btrfs_root *root);
> struct extent_buffer *btrfs_find_tree_block(struct btrfs_fs_info *fs_info,
> u64 bytenr);
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index 23b6e03..861c29f 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -519,8 +519,12 @@ int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode,
> * the disk i_size. There is no need to log the inode
> * at this time.
> */
> - if (end_pos > isize)
> + if (end_pos > isize) {
> i_size_write(inode, end_pos);
> + clear_bit(BTRFS_INODE_NOISIZE, &BTRFS_I(inode)->runtime_flags);
> + } else {
> + set_bit(BTRFS_INODE_NOISIZE, &BTRFS_I(inode)->runtime_flags);
> + }
> return 0;
> }
>
> @@ -1711,19 +1715,33 @@ out:
> static void update_time_for_write(struct inode *inode)
> {
> struct timespec now;
> + int sync_it = 0;
>
> - if (IS_NOCMTIME(inode))
> + if (IS_NOCMTIME(inode)) {
> + set_bit(BTRFS_INODE_NOTIMESTAMP, &BTRFS_I(inode)->runtime_flags);
> return;
> + }
>
> now = current_fs_time(inode->i_sb);
> - if (!timespec_equal(&inode->i_mtime, &now))
> + if (!timespec_equal(&inode->i_mtime, &now)) {
> inode->i_mtime = now;
> + sync_it = S_MTIME;
> + }
>
> - if (!timespec_equal(&inode->i_ctime, &now))
> + if (!timespec_equal(&inode->i_ctime, &now)) {
> inode->i_ctime = now;
> + sync_it |= S_CTIME;
> + }
>
> - if (IS_I_VERSION(inode))
> + if (IS_I_VERSION(inode)) {
> inode_inc_iversion(inode);
> + sync_it |= S_VERSION;
> + }
> +
> + if (!sync_it)
> + set_bit(BTRFS_INODE_NOTIMESTAMP, &BTRFS_I(inode)->runtime_flags);
> + else
> + clear_bit(BTRFS_INODE_NOTIMESTAMP, &BTRFS_I(inode)->runtime_flags);
> }
>
> static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
> @@ -1987,6 +2005,17 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
> goto out;
> }
>
> + if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) {
> + if (test_and_clear_bit(BTRFS_INODE_NOTIMESTAMP,
> + &BTRFS_I(inode)->runtime_flags) &&
> + test_and_clear_bit(BTRFS_INODE_NOISIZE,
> + &BTRFS_I(inode)->runtime_flags)) {
> + barrier_all_devices(root->fs_info);
> + mutex_unlock(&inode->i_mutex);
> + goto out;
Hi Liu,
For the non-full sync case, what happens if an IO error happened
during writeback?
I don't see anything here that checks if an IO error happened and
return -EIO to user space if such error happened.
In other words, testing for the bit AS_EIO in the inode->i_mapping->flags.
thanks
> + }
> + }
> +
> /*
> * ok we haven't committed the transaction yet, lets do a commit
> */
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 0020b56..3d230e6 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -1384,6 +1384,7 @@ out_check:
>
> btrfs_release_path(path);
> if (cow_start != (u64)-1) {
> + clear_bit(BTRFS_INODE_NOISIZE, &BTRFS_I(inode)->runtime_flags);
> ret = cow_file_range(inode, locked_page,
> cow_start, found_key.offset - 1,
> page_started, nr_written, 1);
> @@ -1426,6 +1427,7 @@ out_check:
> em->start + em->len - 1, 0);
> }
> type = BTRFS_ORDERED_PREALLOC;
> + clear_bit(BTRFS_INODE_NOISIZE, &BTRFS_I(inode)->runtime_flags);
> } else {
> type = BTRFS_ORDERED_NOCOW;
> }
> @@ -1464,6 +1466,7 @@ out_check:
> }
>
> if (cow_start != (u64)-1) {
> + clear_bit(BTRFS_INODE_NOISIZE, &BTRFS_I(inode)->runtime_flags);
> ret = cow_file_range(inode, locked_page, cow_start, end,
> page_started, nr_written, 1);
> if (ret)
> --
> 2.1.0
>
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--
Filipe David Manana,
"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."
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