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Commit ad635942 authored by Jeff Layton's avatar Jeff Layton Committed by Steve French
Browse files

cifs: simplify refcounting for oplock breaks 



Currently, we take a sb->s_active reference and a cifsFileInfo reference
when an oplock break workqueue job is queued. This is unnecessary and
more complicated than it needs to be. Also as Al points out,
deactivate_super has non-trivial locking implications so it's best to
avoid that if we can.

Instead, just cancel any pending oplock breaks for this filehandle
synchronously in cifsFileInfo_put after taking it off the lists.
That should ensure that this job doesn't outlive the structures it
depends on.

Reported-by: default avatarAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
parent 5980fc96

fs/cifs/cifsfs.c

+0 −18
Original line number Diff line number Diff line
@@ -86,24 +86,6 @@ extern mempool_t *cifs_sm_req_poolp; 
extern mempool_t *cifs_req_poolp;

extern mempool_t *cifs_mid_poolp;



void

cifs_sb_active(struct super_block *sb)

{

	struct cifs_sb_info *server = CIFS_SB(sb);



	if (atomic_inc_return(&server->active) == 1)

		atomic_inc(&sb->s_active);

}



void

cifs_sb_deactive(struct super_block *sb)

{

	struct cifs_sb_info *server = CIFS_SB(sb);



	if (atomic_dec_and_test(&server->active))

		deactivate_super(sb);

}



static int

cifs_read_super(struct super_block *sb)

{

fs/cifs/cifsfs.h

+0 −4
Original line number Diff line number Diff line
@@ -41,10 +41,6 @@ extern struct file_system_type cifs_fs_type; 
extern const struct address_space_operations cifs_addr_ops;

extern const struct address_space_operations cifs_addr_ops_smallbuf;



/* Functions related to super block operations */

extern void cifs_sb_active(struct super_block *sb);

extern void cifs_sb_deactive(struct super_block *sb);



/* Functions related to inodes */

extern const struct inode_operations cifs_dir_inode_ops;

extern struct inode *cifs_root_iget(struct super_block *);

fs/cifs/cifsglob.h

+0 −2
Original line number Diff line number Diff line
@@ -942,8 +942,6 @@ GLOBAL_EXTERN spinlock_t siduidlock; 
GLOBAL_EXTERN spinlock_t sidgidlock;



void cifs_oplock_break(struct work_struct *work);

void cifs_oplock_break_get(struct cifsFileInfo *cfile);

void cifs_oplock_break_put(struct cifsFileInfo *cfile);



extern const struct slow_work_ops cifs_oplock_break_ops;

fs/cifs/file.c

+2 −25
Original line number Diff line number Diff line
@@ -314,6 +314,8 @@ void cifsFileInfo_put(struct cifsFileInfo *cifs_file) 
	}

	spin_unlock(&cifs_file_list_lock);



	cancel_work_sync(&cifs_file->oplock_break);



	if (!tcon->need_reconnect && !cifs_file->invalidHandle) {

		int xid, rc;
@@ -2418,31 +2420,6 @@ void cifs_oplock_break(struct work_struct *work) 
				 cinode->clientCanCacheRead ? 1 : 0);

		cFYI(1, "Oplock release rc = %d", rc);

	}



	/*

	 * We might have kicked in before is_valid_oplock_break()

	 * finished grabbing reference for us.  Make sure it's done by

	 * waiting for cifs_file_list_lock.

	 */

	spin_lock(&cifs_file_list_lock);

	spin_unlock(&cifs_file_list_lock);



	cifs_oplock_break_put(cfile);

}



/* must be called while holding cifs_file_list_lock */

void cifs_oplock_break_get(struct cifsFileInfo *cfile)

{

	cifs_sb_active(cfile->dentry->d_sb);

	cifsFileInfo_get(cfile);

}



void cifs_oplock_break_put(struct cifsFileInfo *cfile)

{

	struct super_block *sb = cfile->dentry->d_sb;



	cifsFileInfo_put(cfile);

	cifs_sb_deactive(sb);

}



const struct address_space_operations cifs_addr_ops = {

fs/cifs/misc.c

+2 −9
Original line number Diff line number Diff line
@@ -585,15 +585,8 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv) 


				cifs_set_oplock_level(pCifsInode,

					pSMB->OplockLevel ? OPLOCK_READ : 0);

				/*

				 * cifs_oplock_break_put() can't be called

				 * from here.  Get reference after queueing

				 * succeeded.  cifs_oplock_break() will

				 * synchronize using cifs_file_list_lock.

				 */

				if (queue_work(system_nrt_wq,

					       &netfile->oplock_break))

					cifs_oplock_break_get(netfile);

				queue_work(system_nrt_wq,

					   &netfile->oplock_break);

				netfile->oplock_break_cancelled = false;



				spin_unlock(&cifs_file_list_lock);