From: Jeff Layton <jlayton@kernel.org>
To: ceph-devel@vger.kernel.org
Cc: ukernel@gmail.com, idryomov@gmail.com
Subject: [PATCH 5/5] ceph: fold ceph_update_writeable_page into ceph_write_begin
Date: Wed, 16 Sep 2020 13:38:54 -0400 [thread overview]
Message-ID: <20200916173854.330265-6-jlayton@kernel.org> (raw)
In-Reply-To: <20200916173854.330265-1-jlayton@kernel.org>
...and reorganize the loop for better clarity.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/ceph/addr.c | 148 ++++++++++++++++++++++---------------------------
1 file changed, 65 insertions(+), 83 deletions(-)
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index a6c54cfc3fea..89c4d8a9a5eb 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -1251,6 +1251,8 @@ static int context_is_writeable_or_written(struct inode *inode,
* @inode: inode associated with page
* @page: page being dirtied
*
+ * We are only allowed to write into/dirty the page if the page is
+ * clean, or already dirty within the same snap context.
* Returns NULL on success, negative error code on error, and a snapc ref that should be
* waited on otherwise.
*/
@@ -1307,104 +1309,84 @@ ceph_find_incompatible(struct inode *inode, 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(inode, 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(inode, page);
+ if (snapc) {
+ if (IS_ERR(snapc)) {
+ r = PTR_ERR(snapc);
+ 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);
+ put_page(page);
+ page = NULL;
+ 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;
}
--
2.26.2
next prev parent reply other threads:[~2020-09-16 17:40 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 17:38 [PATCH 0/5] ceph: addr.c cleanups Jeff Layton
2020-09-16 17:38 ` [PATCH 1/5] ceph: break out writeback of incompatible snap context to separate function Jeff Layton
2020-09-16 17:38 ` [PATCH 2/5] ceph: don't call ceph_update_writeable_page from page_mkwrite Jeff Layton
2020-09-16 17:38 ` [PATCH 3/5] ceph: fold ceph_sync_readpages into ceph_readpage Jeff Layton
2020-09-16 17:38 ` [PATCH 4/5] ceph: fold ceph_sync_writepages into writepage_nounlock Jeff Layton
2020-09-16 17:38 ` Jeff Layton [this message]
2020-09-16 19:16 ` [PATCH 5/5] ceph: fold ceph_update_writeable_page into ceph_write_begin Jeff Layton
2021-06-11 14:14 ` Andrew W Elble
2021-06-11 14:52 ` Jeff Layton
2021-06-11 15:11 ` David Howells
2021-06-11 15:20 ` Matthew Wilcox
2021-06-11 15:38 ` Jeff Layton
2021-06-11 15:35 ` David Howells
2021-06-11 15:59 ` Andrew W Elble
2021-06-11 17:56 ` Matthew Wilcox
2021-06-11 21:47 ` David Howells
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