Commit 764a1b1a authored by Jeff Layton's avatar Jeff Layton Committed by Steve French
Browse files

cifs: ensure that we always do cifsFileInfo_get under the spinlock 



The readpages bug is a regression that was introduced in 6993f74a.
This also fixes a couple of similar bugs in the uncached read and write
codepaths.

Also, prevent this sort of thing in the future by having cifsFileInfo_get
take the spinlock itself, and adding a _locked variant for use in places
that are already holding the lock. The _put code has always done that
so this makes for a less confusing interface.

Cc: <stable@vger.kernel.org> # 3.5.x
Reviewed-by: default avatarPavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarSteve French <smfrench@gmail.com>
parent 29e20f9c

fs/cifs/cifsglob.h

+3 −3
Original line number Diff line number Diff line
@@ -765,13 +765,13 @@ struct cifs_io_parms { 
 * Take a reference on the file private data. Must be called with

 * cifs_file_list_lock held.

 */

static inline

struct cifsFileInfo *cifsFileInfo_get(struct cifsFileInfo *cifs_file)

static inline void

cifsFileInfo_get_locked(struct cifsFileInfo *cifs_file)

{

	++cifs_file->count;

	return cifs_file;

}



struct cifsFileInfo *cifsFileInfo_get(struct cifsFileInfo *cifs_file);

void cifsFileInfo_put(struct cifsFileInfo *cifs_file);



/*

fs/cifs/file.c

+12 −5
Original line number Diff line number Diff line
@@ -284,6 +284,15 @@ cifs_new_fileinfo(__u16 fileHandle, struct file *file, 


static void cifs_del_lock_waiters(struct cifsLockInfo *lock);



struct cifsFileInfo *

cifsFileInfo_get(struct cifsFileInfo *cifs_file)

{

	spin_lock(&cifs_file_list_lock);

	cifsFileInfo_get_locked(cifs_file);

	spin_unlock(&cifs_file_list_lock);

	return cifs_file;

}



/*

 * Release a reference on the file private data. This may involve closing

 * the filehandle out on the server. Must be called without holding
@@ -1562,7 +1571,7 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode, 
			if (!open_file->invalidHandle) {

				/* found a good file */

				/* lock it so it will not be closed on us */

				cifsFileInfo_get(open_file);

				cifsFileInfo_get_locked(open_file);

				spin_unlock(&cifs_file_list_lock);

				return open_file;

			} /* else might as well continue, and look for
@@ -1614,7 +1623,7 @@ refind_writable: 
		if (OPEN_FMODE(open_file->f_flags) & FMODE_WRITE) {

			if (!open_file->invalidHandle) {

				/* found a good writable file */

				cifsFileInfo_get(open_file);

				cifsFileInfo_get_locked(open_file);

				spin_unlock(&cifs_file_list_lock);

				return open_file;

			} else {
@@ -1631,7 +1640,7 @@ refind_writable: 


	if (inv_file) {

		any_available = false;

		cifsFileInfo_get(inv_file);

		cifsFileInfo_get_locked(inv_file);

	}



	spin_unlock(&cifs_file_list_lock);
@@ -3082,8 +3091,6 @@ static int cifs_readpages(struct file *file, struct address_space *mapping, 
			break;

		}



		spin_lock(&cifs_file_list_lock);

		spin_unlock(&cifs_file_list_lock);

		rdata->cfile = cifsFileInfo_get(open_file);

		rdata->mapping = mapping;

		rdata->offset = offset;

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