When reading a single page with cifs_readpage(), we make a call to
fscache_read_or_alloc_page() which once done, asynchronously calls
the completion function cifs_readpage_from_fscache_complete(). This
completion function unlocks the page once it has been populated from
cache. The module then attempts to unlock the page a second time in
cifs_readpage() which leads to warning messages.
In case of a successful call to fscache_read_or_alloc_page() we should skip
the second unlock_page() since this will be called by the
cifs_readpage_from_fscache_complete() once the page has been populated by
fscache.
With the modifications to cifs_readpage_worker(), we will need to re-grab the
page lock in cifs_write_begin().
Signed-off-by: Sachin Prabhu <sprabhu@xxxxxxxxxx>
---
fs/cifs/file.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 69e8431..98e5222 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3423,6 +3423,7 @@ static int cifs_readpage_worker(struct file *file, struct page *page,
io_error:
kunmap(page);
page_cache_release(page);
+ unlock_page(page);
read_complete:
return rc;
@@ -3447,8 +3448,6 @@ static int cifs_readpage(struct file *file, struct page *page)
rc = cifs_readpage_worker(file, page, &offset);
- unlock_page(page);
-
free_xid(xid);
return rc;
}
@@ -3502,6 +3501,7 @@ static int cifs_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
+ int oncethru = 0;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
loff_t offset = pos & (PAGE_CACHE_SIZE - 1);
loff_t page_start = pos & PAGE_MASK;
@@ -3511,6 +3511,7 @@ static int cifs_write_begin(struct file *file, struct address_space *mapping,
cifs_dbg(FYI, "write_begin from %lld len %d\n", (long long)pos, len);
+start:
page = grab_cache_page_write_begin(mapping, index, flags);
if (!page) {
rc = -ENOMEM;
@@ -3552,13 +3553,16 @@ static int cifs_write_begin(struct file *file, struct address_space *mapping,
}
}
- if ((file->f_flags & O_ACCMODE) != O_WRONLY) {
+ if ((file->f_flags & O_ACCMODE) != O_WRONLY && !oncethru) {
/*
* might as well read a page, it is fast enough. If we get
* an error, we don't need to return it. cifs_write_end will
* do a sync write instead since PG_uptodate isn't set.
*/
cifs_readpage_worker(file, page, &page_start);
+ page_cache_release(page);
+ oncethru = 1;
+ goto start;
} else {
/* we could try using another file handle if there is one -
but how would we lock it to prevent close of that handle
--
1.8.3.1
--
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