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| author | Sachin Prabhu <sprabhu@redhat.com> | 2013-09-13 14:11:57 +0100 |
|---|---|---|
| committer | Steve French <smfrench@gmail.com> | 2013-09-13 16:24:49 -0500 |
| commit | 466bd31bbda9e1dd2ace1d72c8de5045bf6f3bf6 (patch) | |
| tree | a9f0d34082a17ed39a237dfb843441766c550a08 | |
| parent | a9e9b7bc15a32ec5b0679704e70f3ffeecfaadd8 (diff) | |
| download | linux-466bd31bbda9e1dd2ace1d72c8de5045bf6f3bf6.tar.gz linux-466bd31bbda9e1dd2ace1d72c8de5045bf6f3bf6.tar.xz | |
cifs: Avoid calling unlock_page() twice in cifs_readpage() when using fscache
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().
The problem was first noticed when testing new fscache patches for cifs.
https://bugzilla.redhat.com/show_bug.cgi?id=1005737
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
| -rw-r--r-- | fs/cifs/file.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 5f99ee551662..eb955b525e55 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -3419,6 +3419,7 @@ static int cifs_readpage_worker(struct file *file, struct page *page, io_error: kunmap(page); + unlock_page(page); read_complete: return rc; @@ -3443,8 +3444,6 @@ 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; } @@ -3498,6 +3497,7 @@ 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; @@ -3507,6 +3507,7 @@ 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; @@ -3548,13 +3549,16 @@ 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 |