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author | Jeff Layton <jlayton@kernel.org> | 2020-06-05 16:05:17 +0300 |
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committer | Ilya Dryomov <idryomov@gmail.com> | 2020-10-12 16:29:27 +0300 |
commit | 1cc1699070bd8f42111b92e5c8018bd7d52f0003 (patch) | |
tree | 531762e3a5776393580050aa020de1c5500baed8 | |
parent | 6390987f2f4c5dcacb3ef7b9cb2ef5b8fdca3e10 (diff) | |
download | linux-1cc1699070bd8f42111b92e5c8018bd7d52f0003.tar.xz |
ceph: fold ceph_update_writeable_page into ceph_write_begin
...and reorganize the loop for better clarity.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
-rw-r--r-- | fs/ceph/addr.c | 146 |
1 files changed, 63 insertions, 83 deletions
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index 72cbaac68256..97827f68a3e7 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -1306,104 +1306,84 @@ ceph_find_incompatible(struct page *page) /* * We are only allowed to write into/dirty the page if the page is * clean, or already dirty within the same snap context. - * - * called with page locked. - * return success with page locked, - * or any failure (incl -EAGAIN) with page unlocked. */ -static int ceph_update_writeable_page(struct file *file, - loff_t pos, unsigned len, - struct page *page) +static int ceph_write_begin(struct file *file, struct address_space *mapping, + loff_t pos, unsigned len, unsigned flags, + struct page **pagep, void **fsdata) { struct inode *inode = file_inode(file); struct ceph_inode_info *ci = ceph_inode(inode); struct ceph_snap_context *snapc; - loff_t page_off = pos & PAGE_MASK; + struct page *page = NULL; + pgoff_t index = pos >> PAGE_SHIFT; int pos_in_page = pos & ~PAGE_MASK; - int end_in_page = pos_in_page + len; - loff_t i_size; - int r; + int r = 0; -retry_locked: - snapc = ceph_find_incompatible(page); - if (snapc) { - if (IS_ERR(snapc)) { - r = PTR_ERR(snapc); - goto fail_unlock; + dout("write_begin file %p inode %p page %p %d~%d\n", file, inode, page, (int)pos, (int)len); + + for (;;) { + page = grab_cache_page_write_begin(mapping, index, 0); + if (!page) { + r = -ENOMEM; + break; } - unlock_page(page); - ceph_queue_writeback(inode); - r = wait_event_killable(ci->i_cap_wq, - context_is_writeable_or_written(inode, snapc)); - ceph_put_snap_context(snapc); - return -EAGAIN; - } - if (PageUptodate(page)) { - dout(" page %p already uptodate\n", page); - return 0; - } + snapc = ceph_find_incompatible(page); + if (snapc) { + if (IS_ERR(snapc)) { + r = PTR_ERR(snapc); + break; + } + unlock_page(page); + put_page(page); + page = NULL; + ceph_queue_writeback(inode); + r = wait_event_killable(ci->i_cap_wq, + context_is_writeable_or_written(inode, snapc)); + ceph_put_snap_context(snapc); + if (r != 0) + break; + continue; + } - /* full page? */ - if (pos_in_page == 0 && len == PAGE_SIZE) - return 0; + if (PageUptodate(page)) { + dout(" page %p already uptodate\n", page); + break; + } - /* past end of file? */ - i_size = i_size_read(inode); - - if (page_off >= i_size || - (pos_in_page == 0 && (pos+len) >= i_size && - end_in_page - pos_in_page != PAGE_SIZE)) { - dout(" zeroing %p 0 - %d and %d - %d\n", - page, pos_in_page, end_in_page, (int)PAGE_SIZE); - zero_user_segments(page, - 0, pos_in_page, - end_in_page, PAGE_SIZE); - return 0; - } + /* + * In some cases we don't need to read at all: + * - full page write + * - write that lies completely beyond EOF + * - write that covers the the page from start to EOF or beyond it + */ + if ((pos_in_page == 0 && len == PAGE_SIZE) || + (pos >= i_size_read(inode)) || + (pos_in_page == 0 && (pos + len) >= i_size_read(inode))) { + zero_user_segments(page, 0, pos_in_page, + pos_in_page + len, PAGE_SIZE); + break; + } - /* we need to read it. */ - r = ceph_do_readpage(file, page); - if (r < 0) { - if (r == -EINPROGRESS) - return -EAGAIN; - goto fail_unlock; + /* + * We need to read it. If we get back -EINPROGRESS, then the page was + * handed off to fscache and it will be unlocked when the read completes. + * Refind the page in that case so we can reacquire the page lock. Otherwise + * we got a hard error or the read was completed synchronously. + */ + r = ceph_do_readpage(file, page); + if (r != -EINPROGRESS) + break; } - goto retry_locked; -fail_unlock: - unlock_page(page); - return r; -} - -/* - * We are only allowed to write into/dirty the page if the page is - * clean, or already dirty within the same snap context. - */ -static int ceph_write_begin(struct file *file, struct address_space *mapping, - loff_t pos, unsigned len, unsigned flags, - struct page **pagep, void **fsdata) -{ - struct inode *inode = file_inode(file); - struct page *page; - pgoff_t index = pos >> PAGE_SHIFT; - int r; - - do { - /* get a page */ - page = grab_cache_page_write_begin(mapping, index, 0); - if (!page) - return -ENOMEM; - - dout("write_begin file %p inode %p page %p %d~%d\n", file, - inode, page, (int)pos, (int)len); - r = ceph_update_writeable_page(file, pos, len, page); - if (r < 0) + if (r < 0) { + if (page) { + unlock_page(page); put_page(page); - else - *pagep = page; - } while (r == -EAGAIN); - + } + } else { + *pagep = page; + } return r; } |