On Wed, 28 Nov 2012 18:23:45 +0400
Pavel Shilovsky <piastry@xxxxxxxxxxx> 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@xxxxxxxxxxx>
> ---
> 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@xxxxxxxxxx>
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