On Mon, Oct 20 2008, Jens Axboe wrote: > On Sun, Oct 19 2008, Dmitri Monakhov wrote: > > Block device write procedure is different from regular file: > > - Actual write performed without i_mutex. > > - It has no metadata, so generic_osync_inode(O_SYNCMETEDATA) can not livelock. > > - We do not have to worry about S_ISUID/S_ISGID bits. > > I already did an O_DIRECT part of block device splicing [1], I'll fold > this into the splice branch and double check with some testing. > > [1] http://git.kernel.dk/?p=linux-2.6-block.git;a=commitdiff;h=fbb724a0484aba938024d41ca1dd86337d2550c9;hp=08c7910b275a4c580ad646ae8654439c8dfae4c5 The below is what I merged. Note that I changed the naming and made the function look a lot more like the other splice helpers, so it's more apparent how it differs. Let me know if I can add you Signed-off-by to this one (preferably after you test it as well :-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 4d154dc..083198a 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1288,7 +1288,7 @@ new_bio: * Splice to file opened with O_DIRECT. Bypass caching completely and * just go direct-to-bio */ -static ssize_t __block_splice_write(struct pipe_inode_info *pipe, +static ssize_t __block_splice_direct_write(struct pipe_inode_info *pipe, struct file *out, loff_t *ppos, size_t len, unsigned int flags) { @@ -1318,6 +1318,9 @@ static ssize_t __block_splice_write(struct pipe_inode_info *pipe, if (bsd.bio) submit_bio(WRITE, bsd.bio); + if (ret > 0) + *ppos += ret; + return ret; } @@ -1327,12 +1330,11 @@ static ssize_t block_splice_write(struct pipe_inode_info *pipe, { ssize_t ret; - if (out->f_flags & O_DIRECT) { - ret = __block_splice_write(pipe, out, ppos, len, flags); - if (ret > 0) - *ppos += ret; - } else - ret = generic_file_splice_write(pipe, out, ppos, len, flags); + if (out->f_flags & O_DIRECT) + ret = __block_splice_direct_write(pipe, out, ppos, len, flags); + else + ret = generic_file_splice_write_file_nolock(pipe, out, ppos, + len, flags); return ret; } diff --git a/fs/splice.c b/fs/splice.c index 4108264..eb1e1ac 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -788,6 +788,59 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, } /** + * generic_file_splice_write_file_nolock - splice data from a pipe to a file + * @pipe: pipe info + * @out: file to write to + * @ppos: position in @out + * @len: number of bytes to splice + * @flags: splice modifier flags + * + * Description: + * Will either move or copy pages (determined by @flags options) from + * the given pipe inode to the given block device. + * Note: this is like @generic_file_splice_write, except that we + * don't bother locking the output file. Useful for splicing directly + * to a block device. + */ +ssize_t generic_file_splice_write_file_nolock(struct pipe_inode_info *pipe, + struct file *out, loff_t *ppos, + size_t len, unsigned int flags) +{ + struct address_space *mapping = out->f_mapping; + struct inode *inode = mapping->host; + struct splice_desc sd = { + .total_len = len, + .flags = flags, + .pos = *ppos, + .u.file = out, + }; + ssize_t ret; + + mutex_lock(&pipe->inode->i_mutex); + ret = __splice_from_pipe(pipe, &sd, pipe_to_file); + mutex_unlock(&pipe->inode->i_mutex); + + if (ret > 0) { + unsigned long nr_pages; + + *ppos += ret; + nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + + if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { + int er; + + er = sync_page_range_nolock(inode, mapping, *ppos, ret); + if (er) + ret = er; + } + balance_dirty_pages_ratelimited_nr(mapping, nr_pages); + } + + return ret; +} +EXPORT_SYMBOL(generic_file_splice_write_file_nolock); + +/** * generic_file_splice_write_nolock - generic_file_splice_write without mutexes * @pipe: pipe info * @out: file to write to diff --git a/include/linux/fs.h b/include/linux/fs.h index a6a625b..5c9b880 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1957,6 +1957,8 @@ extern ssize_t generic_file_splice_write(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int); extern ssize_t generic_file_splice_write_nolock(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int); +extern ssize_t generic_file_splice_write_file_nolock(struct pipe_inode_info *, + struct file *, loff_t *, size_t, unsigned int); extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, loff_t *, size_t len, unsigned int flags); extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
