From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:29603 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752246AbbFJCJ3 (ORCPT ); Tue, 9 Jun 2015 22:09:29 -0400 Date: Wed, 10 Jun 2015 10:09:08 +0800 From: Liu Bo To: Filipe David Manana Cc: "linux-btrfs@vger.kernel.org" Subject: Re: [RFC PATCH 2/2] Btrfs: improve fsync for nocow file Message-ID: <20150610020906.GA2849@localhost.localdomain> Reply-To: bo.li.liu@oracle.com References: <1433851471-11543-1-git-send-email-bo.li.liu@oracle.com> <1433851471-11543-2-git-send-email-bo.li.liu@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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 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 > > --- > > 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? 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 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > 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."