Commit 15745320 authored by Steve French's avatar Steve French
Browse files

[CIFS] Fix oops in find_writable_file 



There was a case in which find_writable_file was not waiting long enough
under heavy stress when writepages was racing with close of the file
handle being used by the write.

Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
parent 77159b4d

fs/cifs/file.c

+28 −9
Original line number Diff line number Diff line
@@ -467,7 +467,7 @@ static int cifs_reopen_file(struct file *file, int can_flush) 
int cifs_close(struct inode *inode, struct file *file)

{

	int rc = 0;

	int xid;

	int xid, timeout;

	struct cifs_sb_info *cifs_sb;

	struct cifsTconInfo *pTcon;

	struct cifsFileInfo *pSMBFile =
@@ -485,9 +485,9 @@ int cifs_close(struct inode *inode, struct file *file) 
			/* no sense reconnecting to close a file that is

			   already closed */

			if (pTcon->tidStatus != CifsNeedReconnect) {

				int timeout = 2;

				timeout = 2;

				while ((atomic_read(&pSMBFile->wrtPending) != 0)

					 && (timeout < 1000) ) {

					&& (timeout <= 2048)) {

					/* Give write a better chance to get to

					server ahead of the close.  We do not

					want to add a wait_q here as it would
@@ -522,6 +522,23 @@ int cifs_close(struct inode *inode, struct file *file) 
		list_del(&pSMBFile->flist);

		list_del(&pSMBFile->tlist);

		write_unlock(&GlobalSMBSeslock);

		timeout = 10;

		/* We waited above to give the SMBWrite a chance to issue

		   on the wire (so we do not get SMBWrite returning EBADF

		   if writepages is racing with close.  Note that writepages

		   does not specify a file handle, so it is possible for a file

		   to be opened twice, and the application close the "wrong"

		   file handle - in these cases we delay long enough to allow

		   the SMBWrite to get on the wire before the SMB Close.

		   We allow total wait here over 45 seconds, more than

		   oplock break time, and more than enough to allow any write

		   to complete on the server, or to time out on the client */

		while ((atomic_read(&pSMBFile->wrtPending) != 0)

				&& (timeout <= 50000)) {

			cERROR(1, ("writes pending, delay free of handle"));

			msleep(timeout);

			timeout *= 8;

		}

		kfree(pSMBFile->search_resume_name);

		kfree(file->private_data);

		file->private_data = NULL;
@@ -1031,22 +1048,24 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode) 
		     (open_file->pfile->f_flags & O_WRONLY))) {

			atomic_inc(&open_file->wrtPending);

			read_unlock(&GlobalSMBSeslock);

			if ((open_file->invalidHandle) &&

			   (!open_file->closePend) /* BB fixme -since the second clause can not be true remove it BB */) {

			if (open_file->invalidHandle) {

				rc = cifs_reopen_file(open_file->pfile, FALSE);

				/* if it fails, try another handle - might be */

				/* dangerous to hold up writepages with retry */

				if (rc) {

					cFYI(1,

					      ("failed on reopen file in wp"));

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

					read_lock(&GlobalSMBSeslock);

					/* can not use this handle, no write

					pending on this one after all */

					atomic_dec

					     (&open_file->wrtPending);

					atomic_dec(&open_file->wrtPending);

					continue;

				}

			}

			if (open_file->closePend) {

				read_lock(&GlobalSMBSeslock);

				atomic_dec(&open_file->wrtPending);

				continue;

			}

			return open_file;

		}

	}