CIFS: Implement cifs_strict_writev (try #4)

If we don't have Exclusive oplock we write a data to the server.
Also set invalidate_mapping flag on the inode if we wrote something
to the server. Add cifs_iovec_write to let the client write iovec
buffers through CIFSSMBWrite2.

Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 201 insertions, 1 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index d7d65a70678e..0de17c1db608 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -848,7 +848,7 @@ int cifs_lock(struct file *file, int cmd, struct file_lock *pfLock)
 }
 
 /* update the file size (if needed) after a write */
-static void
+void
 cifs_update_eof(struct cifsInodeInfo *cifsi, loff_t offset,
                       unsigned int bytes_written)
 {
@@ -1619,6 +1619,206 @@ int cifs_flush(struct file *file, fl_owner_t id)
         return rc;
 }
 
+static int
+cifs_write_allocate_pages(struct page **pages, unsigned long num_pages)
+{
+        int rc = 0;
+        unsigned long i;
+
+        for (i = 0; i < num_pages; i++) {
+                pages[i] = alloc_page(__GFP_HIGHMEM);
+                if (!pages[i]) {
+                        /*
+                         * save number of pages we have already allocated and
+                         * return with ENOMEM error
+                         */
+                        num_pages = i;
+                        rc = -ENOMEM;
+                        goto error;
+                }
+        }
+
+        return rc;
+
+error:
+        for (i = 0; i < num_pages; i++)
+                put_page(pages[i]);
+        return rc;
+}
+
+static inline
+size_t get_numpages(const size_t wsize, const size_t len, size_t *cur_len)
+{
+        size_t num_pages;
+        size_t clen;
+
+        clen = min_t(const size_t, len, wsize);
+        num_pages = clen / PAGE_CACHE_SIZE;
+        if (clen % PAGE_CACHE_SIZE)
+                num_pages++;
+
+        if (cur_len)
+                *cur_len = clen;
+
+        return num_pages;
+}
+
+static ssize_t
+cifs_iovec_write(struct file *file, const struct iovec *iov,
+                 unsigned long nr_segs, loff_t *poffset)
+{
+        size_t total_written = 0, written = 0;
+        unsigned long num_pages, npages;
+        size_t copied, len, cur_len, i;
+        struct kvec *to_send;
+        struct page **pages;
+        struct iov_iter it;
+        struct inode *inode;
+        struct cifsFileInfo *open_file;
+        struct cifsTconInfo *pTcon;
+        struct cifs_sb_info *cifs_sb;
+        int xid, rc;
+
+        len = iov_length(iov, nr_segs);
+        if (!len)
+                return 0;
+
+        rc = generic_write_checks(file, poffset, &len, 0);
+        if (rc)
+                return rc;
+
+        cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
+        num_pages = get_numpages(cifs_sb->wsize, len, &cur_len);
+
+        pages = kmalloc(sizeof(struct pages *)*num_pages, GFP_KERNEL);
+        if (!pages)
+                return -ENOMEM;
+
+        to_send = kmalloc(sizeof(struct kvec)*(num_pages + 1), GFP_KERNEL);
+        if (!to_send) {
+                kfree(pages);
+                return -ENOMEM;
+        }
+
+        rc = cifs_write_allocate_pages(pages, num_pages);
+        if (rc) {
+                kfree(pages);
+                kfree(to_send);
+                return rc;
+        }
+
+        xid = GetXid();
+        open_file = file->private_data;
+        pTcon = tlink_tcon(open_file->tlink);
+        inode = file->f_path.dentry->d_inode;
+
+        iov_iter_init(&it, iov, nr_segs, len, 0);
+        npages = num_pages;
+
+        do {
+                size_t save_len = cur_len;
+                for (i = 0; i < npages; i++) {
+                        copied = min_t(const size_t, cur_len, PAGE_CACHE_SIZE);
+                        copied = iov_iter_copy_from_user(pages[i], &it, 0,
+                                                         copied);
+                        cur_len -= copied;
+                        iov_iter_advance(&it, copied);
+                        to_send[i+1].iov_base = kmap(pages[i]);
+                        to_send[i+1].iov_len = copied;
+                }
+
+                cur_len = save_len - cur_len;
+
+                do {
+                        if (open_file->invalidHandle) {
+                                rc = cifs_reopen_file(open_file, false);
+                                if (rc != 0)
+                                        break;
+                        }
+                        rc = CIFSSMBWrite2(xid, pTcon, open_file->netfid,
+                                           cur_len, *poffset, &written,
+                                           to_send, npages, 0);
+                } while (rc == -EAGAIN);
+
+                for (i = 0; i < npages; i++)
+                        kunmap(pages[i]);
+
+                if (written) {
+                        len -= written;
+                        total_written += written;
+                        cifs_update_eof(CIFS_I(inode), *poffset, written);
+                        *poffset += written;
+                } else if (rc < 0) {
+                        if (!total_written)
+                                total_written = rc;
+                        break;
+                }
+
+                /* get length and number of kvecs of the next write */
+                npages = get_numpages(cifs_sb->wsize, len, &cur_len);
+        } while (len > 0);
+
+        if (total_written > 0) {
+                spin_lock(&inode->i_lock);
+                if (*poffset > inode->i_size)
+                        i_size_write(inode, *poffset);
+                spin_unlock(&inode->i_lock);
+        }
+
+        cifs_stats_bytes_written(pTcon, total_written);
+        mark_inode_dirty_sync(inode);
+
+        for (i = 0; i < num_pages; i++)
+                put_page(pages[i]);
+        kfree(to_send);
+        kfree(pages);
+        FreeXid(xid);
+        return total_written;
+}
+
+static ssize_t cifs_user_writev(struct kiocb *iocb, const struct iovec *iov,
+                                unsigned long nr_segs, loff_t pos)
+{
+        ssize_t written;
+        struct inode *inode;
+
+        inode = iocb->ki_filp->f_path.dentry->d_inode;
+
+        /*
+         * BB - optimize the way when signing is disabled. We can drop this
+         * extra memory-to-memory copying and use iovec buffers for constructing
+         * write request.
+         */
+
+        written = cifs_iovec_write(iocb->ki_filp, iov, nr_segs, &pos);
+        if (written > 0) {
+                CIFS_I(inode)->invalid_mapping = true;
+                iocb->ki_pos = pos;
+        }
+
+        return written;
+}
+
+ssize_t cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
+                           unsigned long nr_segs, loff_t pos)
+{
+        struct inode *inode;
+
+        inode = iocb->ki_filp->f_path.dentry->d_inode;
+
+        if (CIFS_I(inode)->clientCanCacheAll)
+                return generic_file_aio_write(iocb, iov, nr_segs, pos);
+
+        /*
+         * In strict cache mode we need to write the data to the server exactly
+         * from the pos to pos+len-1 rather than flush all 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.
+         */
+
+        return cifs_user_writev(iocb, iov, nr_segs, pos);
+}
+
 static ssize_t
 cifs_iovec_read(struct file *file, const struct iovec *iov,
                  unsigned long nr_segs, loff_t *poffset)