On Wed, Jun 10, 2015 at 3:09 AM, Liu Bo <bo.li.liu@xxxxxxxxxx> wrote:
> On Tue, Jun 09, 2015 at 01:56:41PM +0100, Filipe David Manana wrote:
>> 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.
>
> Good point, I missed that part.
>
> Besides that, is the whole "noi_version and nocow" idea acceptable to you?
Yes.
I haven't tested it however, just eyeballed the patches.
Thanks.
>
> Thanks,
>
> -liubo
>
>>
>> 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."
--
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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