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ceph: fold ceph_update_writeable_page into ceph_write_begin

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...and reorganize the loop for better clarity.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Jeff Layton 2020-06-05 09:05:17 -04:00 committed by Ilya Dryomov
parent 6390987f2f
commit 1cc1699070
1 changed files with 66 additions and 86 deletions
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152
fs/ceph/addr.c
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@ -1303,78 +1303,6 @@ ceph_find_incompatible(struct page *page)
return NULL;
}
/*
* 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)
{
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;
int pos_in_page = pos & ~PAGE_MASK;
int end_in_page = pos_in_page + len;
loff_t i_size;
int r;
retry_locked:
snapc = ceph_find_incompatible(page);
if (snapc) {
if (IS_ERR(snapc)) {
r = PTR_ERR(snapc);
goto fail_unlock;
}
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;
}
/* full page? */
if (pos_in_page == 0 && len == PAGE_SIZE)
return 0;
/* 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;
}
/* we need to read it. */
r = ceph_do_readpage(file, page);
if (r < 0) {
if (r == -EINPROGRESS)
return -EAGAIN;
goto fail_unlock;
}
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.
@ -1384,26 +1312,78 @@ static int ceph_write_begin(struct file *file, struct address_space *mapping,
struct page **pagep, void **fsdata)
{
struct inode *inode = file_inode(file);
struct page *page;
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_snap_context *snapc;
struct page *page = NULL;
pgoff_t index = pos >> PAGE_SHIFT;
int r;
int pos_in_page = pos & ~PAGE_MASK;
int r = 0;
do {
/* get a page */
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)
return -ENOMEM;
if (!page) {
r = -ENOMEM;
break;
}
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)
snapc = ceph_find_incompatible(page);
if (snapc) {
if (IS_ERR(snapc)) {
r = PTR_ERR(snapc);
break;
}
unlock_page(page);
put_page(page);
else
*pagep = page;
} while (r == -EAGAIN);
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;
}
if (PageUptodate(page)) {
dout(" page %p already uptodate\n", page);
break;
}
/*
* 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. 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;
}
if (r < 0) {
if (page) {
unlock_page(page);
put_page(page);
}
} else {
*pagep = page;
}
return r;
}