diff mbox

[v2,6/6] CIFS: Fix write after setting a read lock for read oplock files

Message ID 1354112625-30315-7-git-send-email-piastry@etersoft.ru (mailing list archive)
State New, archived
Headers show

Commit Message

Pavel Shilovsky Nov. 28, 2012, 2:23 p.m. UTC 
If we have a read oplock and set a read lock in it, we can't write to the
locked area - so, filemap_fdatawrite may fail with a no information for a
userspace application even if we request a write to non-locked area. Fix
this by checking for brlocks, populating the page cache without marking
affected pages dirty and directly writing to the server.

Also remove CONFIG_CIFS_SMB2 ifdefs because it's suitable for both CIFS
and SMB2 protocols.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
---
 fs/cifs/file.c |   63 +++++++++++++++++++++++++++++---------------------------
 1 file changed, 33 insertions(+), 30 deletions(-)

Comments

Jeff Layton Nov. 30, 2012, 6:59 p.m. UTC | #1 
On Wed, 28 Nov 2012 18:23:45 +0400
Pavel Shilovsky <piastry@etersoft.ru> wrote:

> If we have a read oplock and set a read lock in it, we can't write to the
> locked area - so, filemap_fdatawrite may fail with a no information for a
> userspace application even if we request a write to non-locked area. Fix
> this by checking for brlocks, populating the page cache without marking
> affected pages dirty and directly writing to the server.
> 
> Also remove CONFIG_CIFS_SMB2 ifdefs because it's suitable for both CIFS
> and SMB2 protocols.
> 
> Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
> ---
>  fs/cifs/file.c |   63 +++++++++++++++++++++++++++++---------------------------
>  1 file changed, 33 insertions(+), 30 deletions(-)
> 
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index e7fc39c..5cfed9c 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2109,7 +2109,14 @@ static int cifs_write_end(struct file *file, struct address_space *mapping,
>  	} else {
>  		rc = copied;
>  		pos += copied;
> -		set_page_dirty(page);
> +		/*
> +		 * If we don't have write oplock and use the strict cache mode,
> +		 * we can leave pages clean - cifs_strict_writev will send a
> +		 * data to the server itself.
> +		 */
> +		if (CIFS_I(inode)->clientCanCacheAll ||
> +		    !(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO))
> +			set_page_dirty(page);
>  	}
>  
>  	if (rc > 0) {
> @@ -2460,8 +2467,8 @@ ssize_t cifs_user_writev(struct kiocb *iocb, const struct iovec *iov,
>  }
>  
>  static ssize_t
> -cifs_writev(struct kiocb *iocb, const struct iovec *iov,
> -	    unsigned long nr_segs, loff_t pos)
> +cifs_pagecache_writev(struct kiocb *iocb, const struct iovec *iov,
> +		      unsigned long nr_segs, loff_t pos)
>  {
>  	struct file *file = iocb->ki_filp;
>  	struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data;
> @@ -2511,25 +2518,26 @@ cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
>  	struct cifsFileInfo *cfile = (struct cifsFileInfo *)
>  						iocb->ki_filp->private_data;
>  	struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
> +	ssize_t written;
>  
> -#ifdef CONFIG_CIFS_SMB2
> -	/*
> -	 * If we have an oplock for read and want to write a data to the file
> -	 * we need to store it in the page cache and then push it to the server
> -	 * to be sure the next read will get a valid data.
> -	 */
> -	if (!cinode->clientCanCacheAll && cinode->clientCanCacheRead) {
> -		ssize_t written;
> -		int rc;
> -
> -		written = generic_file_aio_write(iocb, iov, nr_segs, pos);
> -		rc = filemap_fdatawrite(inode->i_mapping);
> -		if (rc)
> -			return (ssize_t)rc;
> -
> -		return written;
> +	/* we have a read oplock - need to store a data in the page cache */
> +	if (cinode->clientCanCacheRead) {
> +		if (cap_unix(tcon->ses) &&
> +		    ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) &&
> +		    (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(
> +						tcon->fsUnixInfo.Capability)))
> +			written = generic_file_aio_write(iocb, iov, nr_segs,
> +							 pos);
> +		else
> +			written = cifs_pagecache_writev(iocb, iov, nr_segs,
> +							pos);
> +		/*
> +		 * Errors occured during writing or we have read+write oplock -
> +		 * no need to flush to the server.
> +		 */
> +		if (written < 0 || cinode->clientCanCacheAll)
> +			return written;
>  	}
> -#endif
>  
>  	/*
>  	 * For non-oplocked files in strict cache mode we need to write the data
> @@ -2537,16 +2545,11 @@ cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
>  	 * affected pages because it may cause a error with mandatory locks on
>  	 * these pages but not on the region from pos to ppos+len-1.
>  	 */
> -
> -	if (!cinode->clientCanCacheAll)
> -		return cifs_user_writev(iocb, iov, nr_segs, pos);
> -
> -	if (cap_unix(tcon->ses) &&
> -	    (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
> -	    ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
> -		return generic_file_aio_write(iocb, iov, nr_segs, pos);
> -
> -	return cifs_writev(iocb, iov, nr_segs, pos);
> +	written = cifs_user_writev(iocb, iov, nr_segs, pos);
> +	/* need to restore pos if errors occured */
> +	if (written < 0)
> +		iocb->ki_pos = pos;
> +	return written;
>  }
>  
>  static struct cifs_readdata *

Looks reasonable...

Acked-by: Jeff Layton <jlayton@redhat.com>
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diff mbox

Patch

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index e7fc39c..5cfed9c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2109,7 +2109,14 @@  static int cifs_write_end(struct file *file, struct address_space *mapping,
 	} else {
 		rc = copied;
 		pos += copied;
-		set_page_dirty(page);
+		/*
+		 * If we don't have write oplock and use the strict cache mode,
+		 * we can leave pages clean - cifs_strict_writev will send a
+		 * data to the server itself.
+		 */
+		if (CIFS_I(inode)->clientCanCacheAll ||
+		    !(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO))
+			set_page_dirty(page);
 	}
 
 	if (rc > 0) {
@@ -2460,8 +2467,8 @@  ssize_t cifs_user_writev(struct kiocb *iocb, const struct iovec *iov,
 }
 
 static ssize_t
-cifs_writev(struct kiocb *iocb, const struct iovec *iov,
-	    unsigned long nr_segs, loff_t pos)
+cifs_pagecache_writev(struct kiocb *iocb, const struct iovec *iov,
+		      unsigned long nr_segs, loff_t pos)
 {
 	struct file *file = iocb->ki_filp;
 	struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data;
@@ -2511,25 +2518,26 @@  cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
 	struct cifsFileInfo *cfile = (struct cifsFileInfo *)
 						iocb->ki_filp->private_data;
 	struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
+	ssize_t written;
 
-#ifdef CONFIG_CIFS_SMB2
-	/*
-	 * If we have an oplock for read and want to write a data to the file
-	 * we need to store it in the page cache and then push it to the server
-	 * to be sure the next read will get a valid data.
-	 */
-	if (!cinode->clientCanCacheAll && cinode->clientCanCacheRead) {
-		ssize_t written;
-		int rc;
-
-		written = generic_file_aio_write(iocb, iov, nr_segs, pos);
-		rc = filemap_fdatawrite(inode->i_mapping);
-		if (rc)
-			return (ssize_t)rc;
-
-		return written;
+	/* we have a read oplock - need to store a data in the page cache */
+	if (cinode->clientCanCacheRead) {
+		if (cap_unix(tcon->ses) &&
+		    ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) &&
+		    (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(
+						tcon->fsUnixInfo.Capability)))
+			written = generic_file_aio_write(iocb, iov, nr_segs,
+							 pos);
+		else
+			written = cifs_pagecache_writev(iocb, iov, nr_segs,
+							pos);
+		/*
+		 * Errors occured during writing or we have read+write oplock -
+		 * no need to flush to the server.
+		 */
+		if (written < 0 || cinode->clientCanCacheAll)
+			return written;
 	}
-#endif
 
 	/*
 	 * For non-oplocked files in strict cache mode we need to write the data
@@ -2537,16 +2545,11 @@  cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
 	 * affected pages because it may cause a error with mandatory locks on
 	 * these pages but not on the region from pos to ppos+len-1.
 	 */
-
-	if (!cinode->clientCanCacheAll)
-		return cifs_user_writev(iocb, iov, nr_segs, pos);
-
-	if (cap_unix(tcon->ses) &&
-	    (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
-	    ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
-		return generic_file_aio_write(iocb, iov, nr_segs, pos);
-
-	return cifs_writev(iocb, iov, nr_segs, pos);
+	written = cifs_user_writev(iocb, iov, nr_segs, pos);
+	/* need to restore pos if errors occured */
+	if (written < 0)
+		iocb->ki_pos = pos;
+	return written;
 }
 
 static struct cifs_readdata *