CIFS: Implement cifs_strict_readv (try #4)

Read from the cache if we have at least Level II oplock - otherwise
read from the server. Add cifs_user_readv to let the client read into
iovec buffers.

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

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index e24d966..a8323f1 100644 (file)
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -736,7 +736,7 @@ const struct file_operations cifs_file_ops = {
 const struct file_operations cifs_file_strict_ops = {
        .read = do_sync_read,
        .write = do_sync_write,
-       .aio_read = generic_file_aio_read,
+       .aio_read = cifs_strict_readv,
        .aio_write = cifs_file_aio_write,
        .open = cifs_open,
        .release = cifs_close,
@@ -792,7 +792,7 @@ const struct file_operations cifs_file_nobrl_ops = {
 const struct file_operations cifs_file_strict_nobrl_ops = {
        .read = do_sync_read,
        .write = do_sync_write,
-       .aio_read = generic_file_aio_read,
+       .aio_read = cifs_strict_readv,
        .aio_write = cifs_file_aio_write,
        .open = cifs_open,
        .release = cifs_close,

diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index 710072e..f23206d 100644 (file)
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -81,7 +81,9 @@ extern int cifs_open(struct inode *inode, struct file *file);
 extern int cifs_close(struct inode *inode, struct file *file);
 extern int cifs_closedir(struct inode *inode, struct file *file);
 extern ssize_t cifs_user_read(struct file *file, char __user *read_data,
-                        size_t read_size, loff_t *poffset);
+                             size_t read_size, loff_t *poffset);
+extern ssize_t cifs_strict_readv(struct kiocb *iocb, const struct iovec *iov,
+                                unsigned long nr_segs, loff_t pos);
 extern ssize_t cifs_user_write(struct file *file, const char __user *write_data,
                         size_t write_size, loff_t *poffset);
 extern int cifs_lock(struct file *, int, struct file_lock *);

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 0b32377..d7d65a7 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1619,42 +1619,42 @@ int cifs_flush(struct file *file, fl_owner_t id)
        return rc;
 }
 
-ssize_t cifs_user_read(struct file *file, char __user *read_data,
-       size_t read_size, loff_t *poffset)
+static ssize_t
+cifs_iovec_read(struct file *file, const struct iovec *iov,
+                unsigned long nr_segs, loff_t *poffset)
 {
-       int rc = -EACCES;
-       unsigned int bytes_read = 0;
-       unsigned int total_read = 0;
-       unsigned int current_read_size;
+       int rc;
+       int xid;
+       unsigned int total_read, bytes_read = 0;
+       size_t len, cur_len;
+       int iov_offset = 0;
        struct cifs_sb_info *cifs_sb;
        struct cifsTconInfo *pTcon;
-       int xid;
        struct cifsFileInfo *open_file;
-       char *smb_read_data;
-       char __user *current_offset;
        struct smb_com_read_rsp *pSMBr;
+       char *read_data;
+
+       if (!nr_segs)
+               return 0;
+
+       len = iov_length(iov, nr_segs);
+       if (!len)
+               return 0;
 
        xid = GetXid();
        cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
 
-       if (file->private_data == NULL) {
-               rc = -EBADF;
-               FreeXid(xid);
-               return rc;
-       }
        open_file = file->private_data;
        pTcon = tlink_tcon(open_file->tlink);
 
        if ((file->f_flags & O_ACCMODE) == O_WRONLY)
                cFYI(1, "attempting read on write only file instance");
 
-       for (total_read = 0, current_offset = read_data;
-            read_size > total_read;
-            total_read += bytes_read, current_offset += bytes_read) {
-               current_read_size = min_t(const int, read_size - total_read,
-                                         cifs_sb->rsize);
+       for (total_read = 0; total_read < len; total_read += bytes_read) {
+               cur_len = min_t(const size_t, len - total_read, cifs_sb->rsize);
                rc = -EAGAIN;
-               smb_read_data = NULL;
+               read_data = NULL;
+
                while (rc == -EAGAIN) {
                        int buf_type = CIFS_NO_BUFFER;
                        if (open_file->invalidHandle) {
@@ -1662,27 +1662,25 @@ ssize_t cifs_user_read(struct file *file, char __user *read_data,
                                if (rc != 0)
                                        break;
                        }
-                       rc = CIFSSMBRead(xid, pTcon,
-                                        open_file->netfid,
-                                        current_read_size, *poffset,
-                                        &bytes_read, &smb_read_data,
-                                        &buf_type);
-                       pSMBr = (struct smb_com_read_rsp *)smb_read_data;
-                       if (smb_read_data) {
-                               if (copy_to_user(current_offset,
-                                               smb_read_data +
-                                               4 /* RFC1001 length field */ +
-                                               le16_to_cpu(pSMBr->DataOffset),
-                                               bytes_read))
+                       rc = CIFSSMBRead(xid, pTcon, open_file->netfid,
+                                        cur_len, *poffset, &bytes_read,
+                                        &read_data, &buf_type);
+                       pSMBr = (struct smb_com_read_rsp *)read_data;
+                       if (read_data) {
+                               char *data_offset = read_data + 4 +
+                                               le16_to_cpu(pSMBr->DataOffset);
+                               if (memcpy_toiovecend(iov, data_offset,
+                                                     iov_offset, bytes_read))
                                        rc = -EFAULT;
-
                                if (buf_type == CIFS_SMALL_BUFFER)
-                                       cifs_small_buf_release(smb_read_data);
+                                       cifs_small_buf_release(read_data);
                                else if (buf_type == CIFS_LARGE_BUFFER)
-                                       cifs_buf_release(smb_read_data);
-                               smb_read_data = NULL;
+                                       cifs_buf_release(read_data);
+                               read_data = NULL;
+                               iov_offset += bytes_read;
                        }
                }
+
                if (rc || (bytes_read == 0)) {
                        if (total_read) {
                                break;
@@ -1695,13 +1693,57 @@ ssize_t cifs_user_read(struct file *file, char __user *read_data,
                        *poffset += bytes_read;
                }
        }
+
        FreeXid(xid);
        return total_read;
 }
 
+ssize_t cifs_user_read(struct file *file, char __user *read_data,
+                      size_t read_size, loff_t *poffset)
+{
+       struct iovec iov;
+       iov.iov_base = read_data;
+       iov.iov_len = read_size;
+
+       return cifs_iovec_read(file, &iov, 1, poffset);
+}
+
+static ssize_t cifs_user_readv(struct kiocb *iocb, const struct iovec *iov,
+                              unsigned long nr_segs, loff_t pos)
+{
+       ssize_t read;
+
+       read = cifs_iovec_read(iocb->ki_filp, iov, nr_segs, &pos);
+       if (read > 0)
+               iocb->ki_pos = pos;
+
+       return read;
+}
+
+ssize_t cifs_strict_readv(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)->clientCanCacheRead)
+               return generic_file_aio_read(iocb, iov, nr_segs, pos);
+
+       /*
+        * In strict cache mode we need to read from the server all the time
+        * if we don't have level II oplock because the server can delay mtime
+        * change - so we can't make a decision about inode invalidating.
+        * And we can also fail with pagereading if there are mandatory locks
+        * on pages affected by this read but not on the region from pos to
+        * pos+len-1.
+        */
+
+       return cifs_user_readv(iocb, iov, nr_segs, pos);
+}
 
 static ssize_t cifs_read(struct file *file, char *read_data, size_t read_size,
-       loff_t *poffset)
+                        loff_t *poffset)
 {
        int rc = -EACCES;
        unsigned int bytes_read = 0;