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NFSv4: Convert nfs_lock_and_join_requests() to use nfs_page_find_head_request() 

Hide the locking from nfs_lock_and_join_requests() so that we can
separate out the requirements for swapcache pages.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Trond Myklebust 2017-08-01 12:06:30 -04:00
parent 7e8a30f8b4
commit bd37d6fce1
1 changed files with 20 additions and 15 deletions
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35
fs/nfs/write.c
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@ -154,6 +154,14 @@ static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
}
static struct nfs_page *
nfs_page_private_request(struct page *page)
{
if (!PagePrivate(page))
return NULL;
return (struct nfs_page *)page_private(page);
}
/*
* nfs_page_find_head_request_locked - find head request associated with @page
*
@ -164,11 +172,10 @@ static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
static struct nfs_page *
nfs_page_find_head_request_locked(struct nfs_inode *nfsi, struct page *page)
{
struct nfs_page *req = NULL;
struct nfs_page *req;
if (PagePrivate(page))
req = (struct nfs_page *)page_private(page);
else if (unlikely(PageSwapCache(page)))
req = nfs_page_private_request(page);
if (!req && unlikely(PageSwapCache(page)))
req = nfs_page_search_commits_for_head_request_locked(nfsi,
page);
@ -448,31 +455,29 @@ nfs_lock_and_join_requests(struct page *page)
int ret;
try_again:
if (!(PagePrivate(page) || PageSwapCache(page)))
return NULL;
spin_lock(&inode->i_lock);
/*
* A reference is taken only on the head request which acts as a
* reference to the whole page group - the group will not be destroyed
* until the head reference is released.
*/
head = nfs_page_find_head_request_locked(NFS_I(inode), page);
if (!head) {
spin_unlock(&inode->i_lock);
head = nfs_page_find_head_request(page);
if (!head)
return NULL;
}
/* lock the page head first in order to avoid an ABBA inefficiency */
if (!nfs_lock_request(head)) {
spin_unlock(&inode->i_lock);
ret = nfs_wait_on_request(head);
nfs_release_request(head);
if (ret < 0)
return ERR_PTR(ret);
goto try_again;
}
spin_unlock(&inode->i_lock);
/* Ensure that nobody removed the request before we locked it */
if (head != nfs_page_private_request(page) && !PageSwapCache(page)) {
nfs_unlock_and_release_request(head);
goto try_again;
}
ret = nfs_page_group_lock(head);
if (ret < 0) {
@ -559,7 +564,7 @@ nfs_lock_and_join_requests(struct page *page)
return NULL;
}
/* still holds ref on head from nfs_page_find_head_request_locked
/* still holds ref on head from nfs_page_find_head_request
* and still has lock on head from lock loop */
return head;
}