[CIFS] Defer close of file handle slightly if there are pending writes that

need to get in ahead of it that depend on that file handle. Fixes
occassional bad file handle errors on write with heavy use multiple process
cases.
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/CHANGES

+Version 1.39
+------------
+Defer close of a file handle slightly if pending writes depend on that file handle
+(this reduces the EBADF bad file handle errors that can be logged under heavy
+stress on writes).
+
 Version 1.38
 ------------
 Fix tcp socket retransmission timeouts (e.g. on ENOSPACE from the socket)

fs/cifs/cifsfs.h

@@ -97,5 +97,5 @@ extern ssize_t	cifs_getxattr(struct dentry *, const char *, void *, size_t);
 extern ssize_t	cifs_listxattr(struct dentry *, char *, size_t);
 extern int cifs_ioctl (struct inode * inode, struct file * filep,
 		       unsigned int command, unsigned long arg);
-#define CIFS_VERSION   "1.38"
+#define CIFS_VERSION   "1.39"
 #endif				/* _CIFSFS_H */

fs/cifs/cifsglob.h

@@ -299,6 +299,7 @@ struct cifsFileInfo {
 	struct inode * pInode; /* needed for oplock break */
 	unsigned closePend:1;	/* file is marked to close */
 	unsigned invalidHandle:1;  /* file closed via session abend */
+	atomic_t wrtPending;   /* handle in use - defer close */
 	struct semaphore fh_sem; /* prevents reopen race after dead ses*/
 	char * search_resume_name; /* BB removeme BB */
 	unsigned int resume_name_length; /* BB removeme - field renamed and moved BB */

fs/cifs/file.c

@@ -29,6 +29,7 @@
 #include <linux/pagevec.h>
 #include <linux/smp_lock.h>
 #include <linux/writeback.h>
+#include <linux/delay.h>
 #include <asm/div64.h>
 #include "cifsfs.h"
 #include "cifspdu.h"
@@ -50,6 +51,11 @@ static inline struct cifsFileInfo *cifs_init_private(
 	private_data->pInode = inode;
 	private_data->invalidHandle = FALSE;
 	private_data->closePend = FALSE;
+	/* we have to track num writers to the inode, since writepages
+	does not tell us which handle the write is for so there can
+	be a close (overlapping with write) of the filehandle that
+	cifs_writepages chose to use */
+	atomic_set(&private_data->wrtPending,0); 
 
 	return private_data;
 }
@@ -473,6 +479,20 @@ 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;
+				while((atomic_read(&pSMBFile->wrtPending) != 0)
+					 && (timeout < 1000) ) {
+					/* 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
+					increase the memory utilization as
+					the struct would be in each open file,
+					but this should give enough time to 
+					clear the socket */
+					cERROR(1,("close with pending writes"));
+					msleep(timeout);
+					timeout *= 4;
+				} 
 				write_unlock(&file->f_owner.lock);
 				rc = CIFSSMBClose(xid, pTcon,
 						  pSMBFile->netfid);
@@ -919,9 +939,10 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode)
 		if (open_file->pfile &&
 		    ((open_file->pfile->f_flags & O_RDWR) ||
 		     (open_file->pfile->f_flags & O_WRONLY))) {
+			atomic_inc(&open_file->wrtPending);
 			read_unlock(&GlobalSMBSeslock);
 			if((open_file->invalidHandle) && 
-			   (!open_file->closePend)) {
+			   (!open_file->closePend) /* BB fixme -since the second clause can not be true remove it BB */) {
 				rc = cifs_reopen_file(&cifs_inode->vfs_inode, 
 						      open_file->pfile, FALSE);
 				/* if it fails, try another handle - might be */
@@ -929,6 +950,10 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode)
 				if(rc) {
 					cFYI(1,("failed on reopen file in wp"));
 					read_lock(&GlobalSMBSeslock);
+					/* can not use this handle, no write
+					pending on this one after all */
+					atomic_dec
+					     (&open_file->wrtPending);
 					continue;
 				}
 			}
@@ -981,6 +1006,7 @@ static int cifs_partialpagewrite(struct page *page, unsigned from, unsigned to)
 	if (open_file) {
 		bytes_written = cifs_write(open_file->pfile, write_data,
 					   to-from, &offset);
+		atomic_dec(&open_file->wrtPending);
 		/* Does mm or vfs already set times? */
 		inode->i_atime = inode->i_mtime = current_fs_time(inode->i_sb);
 		if ((bytes_written > 0) && (offset)) {
@@ -1016,7 +1042,7 @@ static int cifs_writepages(struct address_space *mapping,
 	pgoff_t next;
 	int nr_pages;
 	__u64 offset = 0;
-	struct cifsFileInfo *open_file = NULL;
+	struct cifsFileInfo *open_file;
 	struct page *page;
 	struct pagevec pvec;
 	int rc = 0;
@@ -1071,15 +1097,6 @@ retry:
 		int first;
 		unsigned int i;
 
-		if (!open_file) {
-			open_file = find_writable_file(CIFS_I(mapping->host));
-			if (!open_file) {
-				pagevec_release(&pvec);
-				cERROR(1, ("No writable handles for inode"));
-				return -EIO;
-			}
-		}
-
 		first = -1;
 		next = 0;
 		n_iov = 0;
@@ -1155,18 +1172,32 @@ retry:
 				break;
 		}
 		if (n_iov) {
-			rc = CIFSSMBWrite2(xid, cifs_sb->tcon,
-					   open_file->netfid, bytes_to_write,
-					   offset, &bytes_written, iov, n_iov,
-					   1);
-			if (rc || bytes_written < bytes_to_write) {
-				cERROR(1,("CIFSSMBWrite2 returned %d, written = %x",
-					  rc, bytes_written));
-				set_bit(AS_EIO, &mapping->flags);
-				SetPageError(page);
+			/* Search for a writable handle every time we call
+			 * CIFSSMBWrite2.  We can't rely on the last handle
+			 * we used to still be valid
+			 */
+			open_file = find_writable_file(CIFS_I(mapping->host));
+			if (!open_file) {
+				cERROR(1, ("No writable handles for inode"));
+				rc = -EBADF;
 			} else {
-				cifs_stats_bytes_written(cifs_sb->tcon,
-							 bytes_written);
+				rc = CIFSSMBWrite2(xid, cifs_sb->tcon,
+						   open_file->netfid,
+						   bytes_to_write, offset,
+						   &bytes_written, iov, n_iov,
+						   1);
+				atomic_dec(&open_file->wrtPending);
+				if (rc || bytes_written < bytes_to_write) {
+					cERROR(1,("Write2 ret %d, written = %d",
+						  rc, bytes_written));
+					/* BB what if continued retry is
+					   requested via mount flags? */
+					set_bit(AS_EIO, &mapping->flags);
+					SetPageError(page);
+				} else {
+					cifs_stats_bytes_written(cifs_sb->tcon,
+								 bytes_written);
+				}
 			}
 			for (i = 0; i < n_iov; i++) {
 				page = pvec.pages[first + i];
@@ -1788,9 +1819,18 @@ static int cifs_readpage(struct file *file, struct page *page)
    page caching in the current Linux kernel design */
 int is_size_safe_to_change(struct cifsInodeInfo *cifsInode)
 {
-	if (cifsInode && find_writable_file(cifsInode))
+	struct cifsFileInfo *open_file = NULL;
+
+	if (cifsInode)
+		open_file =  find_writable_file(cifsInode);
+ 
+	if(open_file) {
+		/* there is not actually a write pending so let
+		this handle go free and allow it to
+		be closable if needed */
+		atomic_dec(&open_file->wrtPending);
 		return 0;
-	else
+	} else
 		return 1;
 }
 

fs/cifs/inode.c

@@ -1006,6 +1006,7 @@ int cifs_setattr(struct dentry *direntry, struct iattr *attrs)
 			__u32 npid = open_file->pid;
 			rc = CIFSSMBSetFileSize(xid, pTcon, attrs->ia_size,
 						nfid, npid, FALSE);
+			atomic_dec(&open_file->wrtPending);
 			cFYI(1,("SetFSize for attrs rc = %d", rc));
 			if(rc == -EINVAL) {
 				int bytes_written;