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ceph: refactor ceph_write_begin, fix ceph_page_mkwrite

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Originally ceph_page_mkwrite called ceph_write_begin, hoping that
the returned locked page would be the page that it was requested
to mkwrite. Factored out relevant part of ceph_page_mkwrite and
we lock the right page anyway.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Yehuda Sadeh 2010-02-09 11:02:51 -08:00 committed by Sage Weil
parent 972f0d3ab1
commit 4af6b2257e
1 changed files with 51 additions and 29 deletions
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80
fs/ceph/addr.c
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@ -907,15 +907,13 @@ static int context_is_writeable_or_written(struct inode *inode,
* 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)
static int ceph_update_writeable_page(struct file *file,
loff_t pos, unsigned len,
struct page *page)
{
struct inode *inode = file->f_dentry->d_inode;
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;
struct page *page;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
loff_t page_off = pos & PAGE_CACHE_MASK;
int pos_in_page = pos & ~PAGE_CACHE_MASK;
int end_in_page = pos_in_page + len;
@ -923,16 +921,6 @@ static int ceph_write_begin(struct file *file, struct address_space *mapping,
struct ceph_snap_context *snapc;
int r;
/* get a page*/
retry:
page = grab_cache_page_write_begin(mapping, index, 0);
if (!page)
return -ENOMEM;
*pagep = page;
dout("write_begin file %p inode %p page %p %d~%d\n", file,
inode, page, (int)pos, (int)len);
retry_locked:
/* writepages currently holds page lock, but if we change that later, */
wait_on_page_writeback(page);
@ -964,7 +952,7 @@ retry_locked:
wait_event_interruptible(ci->i_cap_wq,
context_is_writeable_or_written(inode, snapc));
ceph_put_snap_context(snapc);
goto retry;
return -EAGAIN;
}
/* yay, writeable, do it now (without dropping page lock) */
@ -1021,6 +1009,35 @@ fail_nosnap:
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->f_dentry->d_inode;
struct page *page;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
int r;
do {
/* get a page*/
page = grab_cache_page_write_begin(mapping, index, 0);
if (!page)
return -ENOMEM;
*pagep = page;
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);
} while (r == -EAGAIN);
return r;
}
/*
* we don't do anything in here that simple_write_end doesn't do
* except adjust dirty page accounting and drop read lock on
@ -1104,8 +1121,6 @@ static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;
loff_t off = page->index << PAGE_CACHE_SHIFT;
loff_t size, len;
struct page *locked_page = NULL;
void *fsdata = NULL;
int ret;
size = i_size_read(inode);
@ -1116,23 +1131,30 @@ static int ceph_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
dout("page_mkwrite %p %llu~%llu page %p idx %lu\n", inode,
off, len, page, page->index);
ret = ceph_write_begin(vma->vm_file, inode->i_mapping, off, len, 0,
&locked_page, &fsdata);
WARN_ON(page != locked_page);
if (!ret) {
/*
* doing the following, instead of calling
* ceph_write_end. Note that we keep the
* page locked
*/
lock_page(page);
ret = VM_FAULT_NOPAGE;
if ((off > size) ||
(page->mapping != inode->i_mapping))
goto out;
ret = ceph_update_writeable_page(vma->vm_file, off, len, page);
if (ret == 0) {
/* success. we'll keep the page locked. */
set_page_dirty(page);
up_read(&mdsc->snap_rwsem);
page_cache_release(page);
ret = VM_FAULT_LOCKED;
} else {
ret = VM_FAULT_SIGBUS;
if (ret == -ENOMEM)
ret = VM_FAULT_OOM;
else
ret = VM_FAULT_SIGBUS;
}
out:
dout("page_mkwrite %p %llu~%llu = %d\n", inode, off, len, ret);
if (ret != VM_FAULT_LOCKED)
unlock_page(page);
return ret;
}