On Wed, Jun 10, 2015 at 9:26 AM, Filipe David Manana <fdmanana@xxxxxxxxx> wrote:
> 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.
I forgot to ask before, but any special reason to use
barrier_all_devices() instead of waiting for the ordered extents in
the given range to get the BTRFS_ORDERED_IO_DONE set?
Using the barrier, wouldn't it wait for all writeback, including those
for other files or for ranges outside the range given to
btrfs_sync_file() (important for msync for e.g.).
thanks
>
> 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."
--
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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