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Commit 4477288a authored by Jeff Layton's avatar Jeff Layton Committed by Steve French
Browse files

cifs: convert GlobalSMBSeslock from a rwlock to regular spinlock 



Convert this lock to a regular spinlock

A rwlock_t offers little value here. It's more expensive than a regular
spinlock unless you have a fairly large section of code that runs under
the read lock and can benefit from the concurrency.

Additionally, we need to ensure that the refcounting for files isn't
racy and to do that we need to lock areas that can increment it for
write. That means that the areas that can actually use a read_lock are
very few and relatively infrequently used.

While we're at it, change the name to something easier to type, and fix
a bug in find_writable_file. cifsFileInfo_put can sleep and shouldn't be
called while holding the lock.

Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Reviewed-by: default avatarSuresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
parent 7a16f196

fs/cifs/cifsfs.c

+1 −1
Original line number Diff line number Diff line
@@ -940,8 +940,8 @@ init_cifs(void) 
	GlobalTotalActiveXid = 0;

	GlobalMaxActiveXid = 0;

	memset(Local_System_Name, 0, 15);

	rwlock_init(&GlobalSMBSeslock);

	rwlock_init(&cifs_tcp_ses_lock);

	spin_lock_init(&cifs_file_list_lock);

	spin_lock_init(&GlobalMid_Lock);



	if (cifs_max_pending < 2) {

fs/cifs/cifsglob.h

+1 −1
Original line number Diff line number Diff line
@@ -720,7 +720,7 @@ GLOBAL_EXTERN rwlock_t cifs_tcp_ses_lock; 
 * If cifs_tcp_ses_lock and the lock below are both needed to be held, then

 * the cifs_tcp_ses_lock must be grabbed first and released last.

 */

GLOBAL_EXTERN rwlock_t GlobalSMBSeslock;

GLOBAL_EXTERN spinlock_t	cifs_file_list_lock;



/* Outstanding dir notify requests */

GLOBAL_EXTERN struct list_head GlobalDnotifyReqList;

fs/cifs/cifssmb.c

+2 −2
Original line number Diff line number Diff line
@@ -91,13 +91,13 @@ static void mark_open_files_invalid(struct cifsTconInfo *pTcon) 
	struct list_head *tmp1;



/* list all files open on tree connection and mark them invalid */

	write_lock(&GlobalSMBSeslock);

	spin_lock(&cifs_file_list_lock);

	list_for_each_safe(tmp, tmp1, &pTcon->openFileList) {

		open_file = list_entry(tmp, struct cifsFileInfo, tlist);

		open_file->invalidHandle = true;

		open_file->oplock_break_cancelled = true;

	}

	write_unlock(&GlobalSMBSeslock);

	spin_unlock(&cifs_file_list_lock);

	/* BB Add call to invalidate_inodes(sb) for all superblocks mounted

	   to this tcon */

}

fs/cifs/file.c

+27 −27
Original line number Diff line number Diff line
@@ -246,14 +246,14 @@ cifs_new_fileinfo(__u16 fileHandle, struct file *file, 
	atomic_set(&pCifsFile->count, 1);

	INIT_WORK(&pCifsFile->oplock_break, cifs_oplock_break);



	write_lock(&GlobalSMBSeslock);

	spin_lock(&cifs_file_list_lock);

	list_add(&pCifsFile->tlist, &(tlink_tcon(tlink)->openFileList));

	/* if readable file instance put first in list*/

	if (file->f_mode & FMODE_READ)

		list_add(&pCifsFile->flist, &pCifsInode->openFileList);

	else

		list_add_tail(&pCifsFile->flist, &pCifsInode->openFileList);

	write_unlock(&GlobalSMBSeslock);

	spin_unlock(&cifs_file_list_lock);



	if ((oplock & 0xF) == OPLOCK_EXCLUSIVE) {

		pCifsInode->clientCanCacheAll = true;
@@ -607,13 +607,13 @@ int cifs_close(struct inode *inode, struct file *file) 
	pTcon = tlink_tcon(pSMBFile->tlink);

	if (pSMBFile) {

		struct cifsLockInfo *li, *tmp;

		write_lock(&GlobalSMBSeslock);

		spin_lock(&cifs_file_list_lock);

		pSMBFile->closePend = true;

		if (pTcon) {

			/* no sense reconnecting to close a file that is

			   already closed */

			if (!pTcon->need_reconnect) {

				write_unlock(&GlobalSMBSeslock);

				spin_unlock(&cifs_file_list_lock);

				timeout = 2;

				while ((atomic_read(&pSMBFile->count) != 1)

					&& (timeout <= 2048)) {
@@ -633,9 +633,9 @@ int cifs_close(struct inode *inode, struct file *file) 
					rc = CIFSSMBClose(xid, pTcon,

						  pSMBFile->netfid);

			} else

				write_unlock(&GlobalSMBSeslock);

				spin_unlock(&cifs_file_list_lock);

		} else

			write_unlock(&GlobalSMBSeslock);

			spin_unlock(&cifs_file_list_lock);



		/* Delete any outstanding lock records.

		   We'll lose them when the file is closed anyway. */
@@ -646,16 +646,16 @@ int cifs_close(struct inode *inode, struct file *file) 
		}

		mutex_unlock(&pSMBFile->lock_mutex);



		write_lock(&GlobalSMBSeslock);

		spin_lock(&cifs_file_list_lock);

		list_del(&pSMBFile->flist);

		list_del(&pSMBFile->tlist);

		write_unlock(&GlobalSMBSeslock);

		spin_unlock(&cifs_file_list_lock);

		cifsFileInfo_put(file->private_data);

		file->private_data = NULL;

	} else

		rc = -EBADF;



	read_lock(&GlobalSMBSeslock);

	spin_lock(&cifs_file_list_lock);

	if (list_empty(&(CIFS_I(inode)->openFileList))) {

		cFYI(1, "closing last open instance for inode %p", inode);

		/* if the file is not open we do not know if we can cache info
@@ -663,7 +663,7 @@ int cifs_close(struct inode *inode, struct file *file) 
		CIFS_I(inode)->clientCanCacheRead = false;

		CIFS_I(inode)->clientCanCacheAll  = false;

	}

	read_unlock(&GlobalSMBSeslock);

	spin_unlock(&cifs_file_list_lock);

	if ((rc == 0) && CIFS_I(inode)->write_behind_rc)

		rc = CIFS_I(inode)->write_behind_rc;

	FreeXid(xid);
@@ -685,18 +685,18 @@ int cifs_closedir(struct inode *inode, struct file *file) 
		struct cifsTconInfo *pTcon = tlink_tcon(pCFileStruct->tlink);



		cFYI(1, "Freeing private data in close dir");

		write_lock(&GlobalSMBSeslock);

		spin_lock(&cifs_file_list_lock);

		if (!pCFileStruct->srch_inf.endOfSearch &&

		    !pCFileStruct->invalidHandle) {

			pCFileStruct->invalidHandle = true;

			write_unlock(&GlobalSMBSeslock);

			spin_unlock(&cifs_file_list_lock);

			rc = CIFSFindClose(xid, pTcon, pCFileStruct->netfid);

			cFYI(1, "Closing uncompleted readdir with rc %d",

				 rc);

			/* not much we can do if it fails anyway, ignore rc */

			rc = 0;

		} else

			write_unlock(&GlobalSMBSeslock);

			spin_unlock(&cifs_file_list_lock);

		ptmp = pCFileStruct->srch_inf.ntwrk_buf_start;

		if (ptmp) {

			cFYI(1, "closedir free smb buf in srch struct");
@@ -1182,7 +1182,7 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode, 
	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))

		fsuid_only = false;



	read_lock(&GlobalSMBSeslock);

	spin_lock(&cifs_file_list_lock);

	/* we could simply get the first_list_entry since write-only entries

	   are always at the end of the list but since the first entry might

	   have a close pending, we go through the whole list */
@@ -1196,7 +1196,7 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode, 
				/* found a good file */

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

				cifsFileInfo_get(open_file);

				read_unlock(&GlobalSMBSeslock);

				spin_unlock(&cifs_file_list_lock);

				return open_file;

			} /* else might as well continue, and look for

			     another, or simply have the caller reopen it
@@ -1204,7 +1204,7 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode, 
		} else /* write only file */

			break; /* write only files are last so must be done */

	}

	read_unlock(&GlobalSMBSeslock);

	spin_unlock(&cifs_file_list_lock);

	return NULL;

}

#endif
@@ -1231,7 +1231,7 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode, 
	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))

		fsuid_only = false;



	read_lock(&GlobalSMBSeslock);

	spin_lock(&cifs_file_list_lock);

refind_writable:

	list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {

		if (open_file->closePend)
@@ -1245,11 +1245,11 @@ refind_writable: 


			if (!open_file->invalidHandle) {

				/* found a good writable file */

				read_unlock(&GlobalSMBSeslock);

				spin_unlock(&cifs_file_list_lock);

				return open_file;

			}



			read_unlock(&GlobalSMBSeslock);

			spin_unlock(&cifs_file_list_lock);

			/* Had to unlock since following call can block */

			rc = cifs_reopen_file(open_file, false);

			if (!rc) {
@@ -1257,7 +1257,7 @@ refind_writable: 
					return open_file;

				else { /* start over in case this was deleted */

				       /* since the list could be modified */

					read_lock(&GlobalSMBSeslock);

					spin_lock(&cifs_file_list_lock);

					cifsFileInfo_put(open_file);

					goto refind_writable;

				}
@@ -1271,7 +1271,7 @@ refind_writable: 
			to hold up writepages here (rather than

			in caller) with continuous retries */

			cFYI(1, "wp failed on reopen file");

			read_lock(&GlobalSMBSeslock);

			spin_lock(&cifs_file_list_lock);

			/* can not use this handle, no write

			   pending on this one after all */

			cifsFileInfo_put(open_file);
@@ -1292,7 +1292,7 @@ refind_writable: 
		any_available = true;

		goto refind_writable;

	}

	read_unlock(&GlobalSMBSeslock);

	spin_unlock(&cifs_file_list_lock);

	return NULL;

}
@@ -2200,16 +2200,16 @@ static int is_inode_writable(struct cifsInodeInfo *cifs_inode) 
{

	struct cifsFileInfo *open_file;



	read_lock(&GlobalSMBSeslock);

	spin_lock(&cifs_file_list_lock);

	list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {

		if (open_file->closePend)

			continue;

		if (OPEN_FMODE(open_file->f_flags) & FMODE_WRITE) {

			read_unlock(&GlobalSMBSeslock);

			spin_unlock(&cifs_file_list_lock);

			return 1;

		}

	}

	read_unlock(&GlobalSMBSeslock);

	spin_unlock(&cifs_file_list_lock);

	return 0;

}
@@ -2373,8 +2373,8 @@ void cifs_oplock_break(struct work_struct *work) 
	 * finished grabbing reference for us.  Make sure it's done by

	 * waiting for GlobalSMSSeslock.

	 */

	write_lock(&GlobalSMBSeslock);

	write_unlock(&GlobalSMBSeslock);

	spin_lock(&cifs_file_list_lock);

	spin_unlock(&cifs_file_list_lock);



	cifs_oplock_break_put(cfile);

}

fs/cifs/misc.c

+4 −4
Original line number Diff line number Diff line
@@ -560,7 +560,7 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv) 
				continue;



			cifs_stats_inc(&tcon->num_oplock_brks);

			read_lock(&GlobalSMBSeslock);

			spin_lock(&cifs_file_list_lock);

			list_for_each(tmp2, &tcon->openFileList) {

				netfile = list_entry(tmp2, struct cifsFileInfo,

						     tlist);
@@ -572,7 +572,7 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv) 
				 * closed anyway.

				 */

				if (netfile->closePend) {

					read_unlock(&GlobalSMBSeslock);

					spin_unlock(&cifs_file_list_lock);

					read_unlock(&cifs_tcp_ses_lock);

					return true;

				}
@@ -594,11 +594,11 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv) 
					cifs_oplock_break_get(netfile);

				netfile->oplock_break_cancelled = false;



				read_unlock(&GlobalSMBSeslock);

				spin_unlock(&cifs_file_list_lock);

				read_unlock(&cifs_tcp_ses_lock);

				return true;

			}

			read_unlock(&GlobalSMBSeslock);

			spin_unlock(&cifs_file_list_lock);

			read_unlock(&cifs_tcp_ses_lock);

			cFYI(1, "No matching file for oplock break");

			return true;