Hi Jens, This RFC DRAFT patch is on top of your "[PATCH v2] Support for write stream IDs" I throw it out early to get comments if it's the way to go.
Quote LWN(http://lwn.net/Articles/638722): "There would be clear value in a closer association between stream IDs and specific buffered-write operations. Getting there would require storing the stream ID with each dirtied page, though; that, in turn, almost certainly implies shoehorning the stream ID into the associated page structure. That would not be an easy task; it is not surprising that it is not a part of this patch set. Should the lack of per-buffered-write stream IDs prove to be a serious constraint in the future, somebody will certainly be motivated to try to find a place to store another eight bits in struct page." This draft patch stores stream_id in buffer head instead of page. --- fs/buffer.c | 4 ++-- fs/ext4/page-io.c | 2 +- fs/mpage.c | 5 ++++- include/linux/buffer_head.h | 1 + mm/filemap.c | 17 +++++++++++++++++ 5 files changed, 25 insertions(+), 4 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index 5191523..274fcc5 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1774,7 +1774,7 @@ static int __block_write_full_page(struct inode *inode, struct page *page, do { struct buffer_head *next = bh->b_this_page; if (buffer_async_write(bh)) { - _submit_bh(write_op, bh, streamid_to_flags(inode_streamid(inode))); + _submit_bh(write_op, bh, streamid_to_flags(bh->b_streamid)); nr_underway++; } bh = next; @@ -1828,7 +1828,7 @@ recover: struct buffer_head *next = bh->b_this_page; if (buffer_async_write(bh)) { clear_buffer_dirty(bh); - _submit_bh(write_op, bh, streamid_to_flags(inode_streamid(inode))); + _submit_bh(write_op, bh, streamid_to_flags(bh->b_streamid)); nr_underway++; } bh = next; diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 980c5a9..c912129 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -406,7 +406,7 @@ submit_and_retry: ret = io_submit_init_bio(io, bh); if (ret) return ret; - bio_set_streamid(io->io_bio, inode_streamid(inode)); + bio_set_streamid(io->io_bio, bh->b_streamid); } ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh)); if (ret != bh->b_size) diff --git a/fs/mpage.c b/fs/mpage.c index fba13f4..1c5ae1c 100644 --- a/fs/mpage.c +++ b/fs/mpage.c @@ -481,12 +481,15 @@ static int __mpage_writepage(struct page *page, struct writeback_control *wbc, int length; struct buffer_head map_bh; loff_t i_size = i_size_read(inode); + int streamid = 0; int ret = 0; if (page_has_buffers(page)) { struct buffer_head *head = page_buffers(page); struct buffer_head *bh = head; + streamid = bh->b_streamid; + /* If they're all mapped and dirty, do it */ page_block = 0; do { @@ -605,7 +608,7 @@ alloc_new: bio_get_nr_vecs(bdev), GFP_NOFS|__GFP_HIGH); if (bio == NULL) goto confused; - bio_set_streamid(bio, inode_streamid(inode)); + bio_set_streamid(bio, streamid); } /* diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 73b4522..5dbb460 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -75,6 +75,7 @@ struct buffer_head { struct address_space *b_assoc_map; /* mapping this buffer is associated with */ atomic_t b_count; /* users using this buffer_head */ + unsigned int b_streamid; }; /* diff --git a/mm/filemap.c b/mm/filemap.c index 6bf5e42..3a31b95 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2419,6 +2419,21 @@ struct page *grab_cache_page_write_begin(struct address_space *mapping, } EXPORT_SYMBOL(grab_cache_page_write_begin); +static void buffer_head_set_streamid(struct page *page, struct file *file) +{ + struct buffer_head *bh, *head; + + if (!page_has_buffers(page)) + return; + + head = page_buffers(page); + bh = head; + do { + bh->b_streamid = file->f_streamid; + bh = bh->b_this_page; + } while (bh != head); +} + ssize_t generic_perform_write(struct file *file, struct iov_iter *i, loff_t pos) { @@ -2466,6 +2481,8 @@ again: if (unlikely(status < 0)) break; + buffer_head_set_streamid(page, file); + if (mapping_writably_mapped(mapping)) flush_dcache_page(page); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
