From 485ddb4b9741bafb70b22e5c1f9b4f37dc3e85bd Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Tue, 27 Mar 2007 08:55:08 +0200 Subject: 1/2 splice: dont steal Stealing pages with splice is problematic because we cannot just insert an uptodate page into the pagecache and hope the filesystem can take care of it later. We also cannot just ClearPageUptodate, then hope prepare_write does not write anything into the page, because I don't think prepare_write gives that guarantee. Remove support for SPLICE_F_MOVE for now. If we really want to bring it back, we might be able to do so with a the new filesystem buffered write aops APIs I'm working on. If we really don't want to bring it back, then we should decide that sooner rather than later, and remove the flag and all the stealing infrastructure before anybody starts using it. Signed-off-by: Nick Piggin Signed-off-by: Jens Axboe --- fs/splice.c | 101 +++++++++++++++++++++++------------------------------------- 1 file changed, 38 insertions(+), 63 deletions(-) (limited to 'fs') diff --git a/fs/splice.c b/fs/splice.c index 2fca6ebf4cc..badc78ff124 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -576,76 +576,51 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, if (this_len + offset > PAGE_CACHE_SIZE) this_len = PAGE_CACHE_SIZE - offset; - /* - * Reuse buf page, if SPLICE_F_MOVE is set and we are doing a full - * page. - */ - if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) { +find_page: + page = find_lock_page(mapping, index); + if (!page) { + ret = -ENOMEM; + page = page_cache_alloc_cold(mapping); + if (unlikely(!page)) + goto out_ret; + /* - * If steal succeeds, buf->page is now pruned from the - * pagecache and we can reuse it. The page will also be - * locked on successful return. + * This will also lock the page */ - if (buf->ops->steal(pipe, buf)) - goto find_page; - - page = buf->page; - if (add_to_page_cache(page, mapping, index, GFP_KERNEL)) { - unlock_page(page); - goto find_page; - } - - page_cache_get(page); - - if (!(buf->flags & PIPE_BUF_FLAG_LRU)) - lru_cache_add(page); - } else { -find_page: - page = find_lock_page(mapping, index); - if (!page) { - ret = -ENOMEM; - page = page_cache_alloc_cold(mapping); - if (unlikely(!page)) - goto out_ret; + ret = add_to_page_cache_lru(page, mapping, index, + GFP_KERNEL); + if (unlikely(ret)) + goto out; + } - /* - * This will also lock the page - */ - ret = add_to_page_cache_lru(page, mapping, index, - GFP_KERNEL); + /* + * We get here with the page locked. If the page is also + * uptodate, we don't need to do more. If it isn't, we + * may need to bring it in if we are not going to overwrite + * the full page. + */ + if (!PageUptodate(page)) { + if (this_len < PAGE_CACHE_SIZE) { + ret = mapping->a_ops->readpage(file, page); if (unlikely(ret)) goto out; - } - /* - * We get here with the page locked. If the page is also - * uptodate, we don't need to do more. If it isn't, we - * may need to bring it in if we are not going to overwrite - * the full page. - */ - if (!PageUptodate(page)) { - if (this_len < PAGE_CACHE_SIZE) { - ret = mapping->a_ops->readpage(file, page); - if (unlikely(ret)) - goto out; - - lock_page(page); - - if (!PageUptodate(page)) { - /* - * Page got invalidated, repeat. - */ - if (!page->mapping) { - unlock_page(page); - page_cache_release(page); - goto find_page; - } - ret = -EIO; - goto out; + lock_page(page); + + if (!PageUptodate(page)) { + /* + * Page got invalidated, repeat. + */ + if (!page->mapping) { + unlock_page(page); + page_cache_release(page); + goto find_page; } - } else - SetPageUptodate(page); - } + ret = -EIO; + goto out; + } + } else + SetPageUptodate(page); } ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len); -- cgit v1.2.3 From 08c72591636829d40bd695d43ec6d2a8191b668b Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Tue, 27 Mar 2007 08:55:39 +0200 Subject: 2/2 splice: dont readpage Splice does not need to readpage to bring the page uptodate before writing to it, because prepare_write will take care of that for us. Splice is also wrong to SetPageUptodate before the page is actually uptodate. This results in the old uninitialised memory leak. This gets fixed as a matter of course when removing the readpage logic. Signed-off-by: Nick Piggin Signed-off-by: Jens Axboe --- fs/splice.c | 30 ------------------------------ 1 file changed, 30 deletions(-) (limited to 'fs') diff --git a/fs/splice.c b/fs/splice.c index badc78ff124..ae50208e3e6 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -593,36 +593,6 @@ find_page: goto out; } - /* - * We get here with the page locked. If the page is also - * uptodate, we don't need to do more. If it isn't, we - * may need to bring it in if we are not going to overwrite - * the full page. - */ - if (!PageUptodate(page)) { - if (this_len < PAGE_CACHE_SIZE) { - ret = mapping->a_ops->readpage(file, page); - if (unlikely(ret)) - goto out; - - lock_page(page); - - if (!PageUptodate(page)) { - /* - * Page got invalidated, repeat. - */ - if (!page->mapping) { - unlock_page(page); - page_cache_release(page); - goto find_page; - } - ret = -EIO; - goto out; - } - } else - SetPageUptodate(page); - } - ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len); if (unlikely(ret)) { loff_t isize = i_size_read(mapping->host); -- cgit v1.2.3 From 40bee44eaef91b6030037c8bb47f909181fb1edc Mon Sep 17 00:00:00 2001 From: Mark Fasheh Date: Wed, 21 Mar 2007 13:11:02 +0100 Subject: Export __splice_from_pipe() Ocfs2 wants to implement it's own splice write actor so that it can better manage cluster / page locks. This lets us re-use the rest of splice write while only providing our own code where it's actually important. Signed-off-by: Mark Fasheh Signed-off-by: Jens Axboe --- fs/splice.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'fs') diff --git a/fs/splice.c b/fs/splice.c index ae50208e3e6..07f6556add0 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -651,9 +651,9 @@ out_ret: * key here is the 'actor' worker passed in that actually moves the data * to the wanted destination. See pipe_to_file/pipe_to_sendpage above. */ -static ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, - struct file *out, loff_t *ppos, size_t len, - unsigned int flags, splice_actor *actor) +ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, + struct file *out, loff_t *ppos, size_t len, + unsigned int flags, splice_actor *actor) { int ret, do_wakeup, err; struct splice_desc sd; @@ -747,6 +747,7 @@ static ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, return ret; } +EXPORT_SYMBOL(__splice_from_pipe); ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, loff_t *ppos, size_t len, unsigned int flags, -- cgit v1.2.3