On Fri, 5 Nov 2010 11:29:34 +0300 Pavel Shilovsky <[email protected]> wrote:
> On strict cache mode if we don't have Exclusive oplock we write a data to > the server through cifs_user_write. Then if we Level II oplock store it in > the cache, otherwise - invalidate inode pages affected by this writing. > > Signed-off-by: Pavel Shilovsky <[email protected]> > --- > fs/cifs/cifsfs.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++----- > fs/cifs/file.c | 14 ++++++++++++-- > 2 files changed, 58 insertions(+), 7 deletions(-) > > diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c > index bb7f36e..fbcd219 100644 > --- a/fs/cifs/cifsfs.c > +++ b/fs/cifs/cifsfs.c > @@ -596,12 +596,53 @@ static ssize_t cifs_file_aio_read(struct kiocb *iocb, > const struct iovec *iov, > static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec > *iov, > unsigned long nr_segs, loff_t pos) > { > - struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode; > - ssize_t written; > + struct inode *inode; > + struct cifs_sb_info *cifs_sb; > + ssize_t written, cache_written; > + loff_t saved_pos; > + > + inode = iocb->ki_filp->f_path.dentry->d_inode; > + > + if (CIFS_I(inode)->clientCanCacheAll) > + return generic_file_aio_write(iocb, iov, nr_segs, pos); > + > + cifs_sb = CIFS_SB(iocb->ki_filp->f_path.dentry->d_sb); > + > + if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) == 0) { > + int rc; > + > + written = generic_file_aio_write(iocb, iov, nr_segs, pos); > + > + rc = filemap_fdatawrite(inode->i_mapping); > + if (rc) > + cFYI(1, "cifs_file_aio_write: %d rc on %p inode", > + rc, inode); > + return written; > + } > + > + saved_pos = pos; > + written = cifs_user_write(iocb->ki_filp, iov->iov_base, > + iov->iov_len, &pos); > + > + if (written > 0 && CIFS_I(inode)->clientCanCacheRead) { > + /* we have data written to the server and at least oplock > + for reading - store the date in the cache */ > + cache_written = generic_file_aio_write(iocb, iov, > + nr_segs, saved_pos); > + if (cache_written != written) > + cERROR(1, "Cache written and server written data " > + "lengths are different"); > + return written; > + } > + > + if (written > 0) > + invalidate_mapping_pages(inode->i_mapping, > + saved_pos >> PAGE_CACHE_SHIFT, > + (saved_pos+iov->iov_len-1) > + >> PAGE_CACHE_SHIFT); > + > + iocb->ki_pos = pos; > > - written = generic_file_aio_write(iocb, iov, nr_segs, pos); > - if (!CIFS_I(inode)->clientCanCacheAll) > - filemap_fdatawrite(inode->i_mapping); > return written; > } > > diff --git a/fs/cifs/file.c b/fs/cifs/file.c > index b36de2e..85824c0 100644 > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c > @@ -1537,7 +1537,11 @@ static int cifs_write_end(struct file *file, struct > address_space *mapping, > struct page *page, void *fsdata) > { > int rc; > - struct inode *inode = mapping->host; > + struct inode *inode; > + struct cifs_sb_info *cifs_sb; > + > + inode = mapping->host; > + cifs_sb = CIFS_SB(inode->i_sb); > > cFYI(1, "write_end for page %p from pos %lld with %d bytes", > page, pos, copied); > @@ -1570,7 +1574,13 @@ static int cifs_write_end(struct file *file, struct > address_space *mapping, > } else { > rc = copied; > pos += copied; > - set_page_dirty(page); > + /* if we have strict cache switched on and don't have Exclusive > + oplock for the inode, we don't have to set_page_dirty > + because we flushed the data to the server in > + cifs_file_aio_write before */ > + if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) == 0 || > + CIFS_I(inode)->clientCanCacheAll) > + set_page_dirty(page); Is there a potential for a race here? Suppose I have clientCanCacheAll set, I write to the cache, but before I get to cifs_write_end, an oplock break is processed and clientCanCacheAll is cleared. Now I have dirty data in cache but the dirty flag doesn't get set. Does anything prevent that? > } > > if (rc > 0) { -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
