forked from Minki/linux
CIFS: Add support for direct I/O read
With direct I/O read, we transfer the data directly from transport layer to the user data buffer. Change in v3: add support for kernel AIO Change in v4: Refactor common read code to __cifs_readv for direct and non-direct I/O. Retry on direct I/O failure. Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Long Li
Steve French
parent
0df444a00f
commit
6e6e2b86c2
@ -101,6 +101,7 @@ extern int cifs_open(struct inode *inode, struct file *file);
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extern int cifs_close(struct inode *inode, struct file *file);
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extern int cifs_closedir(struct inode *inode, struct file *file);
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extern ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to);
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extern ssize_t cifs_direct_readv(struct kiocb *iocb, struct iov_iter *to);
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extern ssize_t cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to);
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extern ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from);
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extern ssize_t cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from);
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@ -1186,6 +1186,11 @@ struct cifs_aio_ctx {
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unsigned int len;
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unsigned int total_len;
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bool should_dirty;
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/*
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* Indicates if this aio_ctx is for direct_io,
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* If yes, iter is a copy of the user passed iov_iter
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*/
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bool direct_io;
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};
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struct cifs_readdata;
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175
fs/cifs/file.c
175
fs/cifs/file.c
@ -2979,7 +2979,6 @@ cifs_uncached_readdata_release(struct kref *refcount)
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kref_put(&rdata->ctx->refcount, cifs_aio_ctx_release);
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for (i = 0; i < rdata->nr_pages; i++) {
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put_page(rdata->pages[i]);
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rdata->pages[i] = NULL;
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}
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cifs_readdata_release(refcount);
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}
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@ -3106,6 +3105,67 @@ cifs_uncached_copy_into_pages(struct TCP_Server_Info *server,
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return uncached_fill_pages(server, rdata, iter, iter->count);
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}
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static int cifs_resend_rdata(struct cifs_readdata *rdata,
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struct list_head *rdata_list,
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struct cifs_aio_ctx *ctx)
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{
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int wait_retry = 0;
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unsigned int rsize, credits;
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int rc;
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struct TCP_Server_Info *server =
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tlink_tcon(rdata->cfile->tlink)->ses->server;
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/*
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* Try to resend this rdata, waiting for credits up to 3 seconds.
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* Note: we are attempting to resend the whole rdata not in segments
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*/
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do {
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rc = server->ops->wait_mtu_credits(server, rdata->bytes,
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&rsize, &credits);
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if (rc)
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break;
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if (rsize < rdata->bytes) {
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add_credits_and_wake_if(server, credits, 0);
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msleep(1000);
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wait_retry++;
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}
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} while (rsize < rdata->bytes && wait_retry < 3);
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/*
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* If we can't find enough credits to send this rdata
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* release the rdata and return failure, this will pass
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* whatever I/O amount we have finished to VFS.
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*/
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if (rsize < rdata->bytes) {
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rc = -EBUSY;
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goto out;
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}
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rc = -EAGAIN;
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while (rc == -EAGAIN) {
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rc = 0;
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if (rdata->cfile->invalidHandle)
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rc = cifs_reopen_file(rdata->cfile, true);
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if (!rc)
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rc = server->ops->async_readv(rdata);
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}
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if (!rc) {
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/* Add to aio pending list */
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list_add_tail(&rdata->list, rdata_list);
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return 0;
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}
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add_credits_and_wake_if(server, rdata->credits, 0);
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out:
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kref_put(&rdata->refcount,
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cifs_uncached_readdata_release);
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return rc;
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}
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static int
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cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
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struct cifs_sb_info *cifs_sb, struct list_head *rdata_list,
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@ -3117,6 +3177,9 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
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int rc;
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pid_t pid;
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struct TCP_Server_Info *server;
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struct page **pagevec;
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size_t start;
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struct iov_iter direct_iov = ctx->iter;
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server = tlink_tcon(open_file->tlink)->ses->server;
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@ -3125,6 +3188,9 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
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else
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pid = current->tgid;
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if (ctx->direct_io)
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iov_iter_advance(&direct_iov, offset - ctx->pos);
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do {
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rc = server->ops->wait_mtu_credits(server, cifs_sb->rsize,
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&rsize, &credits);
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@ -3132,8 +3198,42 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
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break;
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cur_len = min_t(const size_t, len, rsize);
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npages = DIV_ROUND_UP(cur_len, PAGE_SIZE);
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if (ctx->direct_io) {
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cur_len = iov_iter_get_pages_alloc(
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&direct_iov, &pagevec,
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cur_len, &start);
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if (cur_len < 0) {
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cifs_dbg(VFS,
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"couldn't get user pages (cur_len=%zd)"
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" iter type %d"
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" iov_offset %zd count %zd\n",
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cur_len, direct_iov.type,
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direct_iov.iov_offset,
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direct_iov.count);
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dump_stack();
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break;
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}
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iov_iter_advance(&direct_iov, cur_len);
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rdata = cifs_readdata_direct_alloc(
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pagevec, cifs_uncached_readv_complete);
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if (!rdata) {
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add_credits_and_wake_if(server, credits, 0);
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rc = -ENOMEM;
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break;
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}
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npages = (cur_len + start + PAGE_SIZE-1) / PAGE_SIZE;
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rdata->page_offset = start;
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rdata->tailsz = npages > 1 ?
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cur_len-(PAGE_SIZE-start)-(npages-2)*PAGE_SIZE :
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cur_len;
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} else {
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npages = DIV_ROUND_UP(cur_len, PAGE_SIZE);
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/* allocate a readdata struct */
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rdata = cifs_readdata_alloc(npages,
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cifs_uncached_readv_complete);
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@ -3147,13 +3247,15 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
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if (rc)
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goto error;
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rdata->tailsz = PAGE_SIZE;
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}
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rdata->cfile = cifsFileInfo_get(open_file);
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rdata->nr_pages = npages;
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rdata->offset = offset;
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rdata->bytes = cur_len;
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rdata->pid = pid;
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rdata->pagesz = PAGE_SIZE;
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rdata->tailsz = PAGE_SIZE;
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rdata->read_into_pages = cifs_uncached_read_into_pages;
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rdata->copy_into_pages = cifs_uncached_copy_into_pages;
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rdata->credits = credits;
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@ -3168,8 +3270,10 @@ error:
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add_credits_and_wake_if(server, rdata->credits, 0);
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kref_put(&rdata->refcount,
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cifs_uncached_readdata_release);
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if (rc == -EAGAIN)
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if (rc == -EAGAIN) {
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iov_iter_revert(&direct_iov, cur_len);
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continue;
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}
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break;
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}
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@ -3225,6 +3329,8 @@ again:
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* reading.
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*/
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if (got_bytes && got_bytes < rdata->bytes) {
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rc = 0;
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if (!ctx->direct_io)
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rc = cifs_readdata_to_iov(rdata, to);
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if (rc) {
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kref_put(&rdata->refcount,
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@ -3233,30 +3339,44 @@ again:
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}
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}
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if (ctx->direct_io) {
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/*
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* Re-use rdata as this is a
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* direct I/O
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*/
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rc = cifs_resend_rdata(
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rdata,
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&tmp_list, ctx);
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} else {
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rc = cifs_send_async_read(
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rdata->offset + got_bytes,
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rdata->bytes - got_bytes,
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rdata->cfile, cifs_sb,
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&tmp_list, ctx);
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list_splice(&tmp_list, &ctx->list);
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kref_put(&rdata->refcount,
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cifs_uncached_readdata_release);
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}
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list_splice(&tmp_list, &ctx->list);
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goto again;
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} else if (rdata->result)
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rc = rdata->result;
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else
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else if (!ctx->direct_io)
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rc = cifs_readdata_to_iov(rdata, to);
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/* if there was a short read -- discard anything left */
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if (rdata->got_bytes && rdata->got_bytes < rdata->bytes)
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rc = -ENODATA;
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ctx->total_len += rdata->got_bytes;
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}
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list_del_init(&rdata->list);
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kref_put(&rdata->refcount, cifs_uncached_readdata_release);
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}
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if (!ctx->direct_io) {
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for (i = 0; i < ctx->npages; i++) {
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if (ctx->should_dirty)
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set_page_dirty(ctx->bv[i].bv_page);
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@ -3264,6 +3384,7 @@ again:
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}
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ctx->total_len = ctx->len - iov_iter_count(to);
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}
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cifs_stats_bytes_read(tcon, ctx->total_len);
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@ -3281,18 +3402,28 @@ again:
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complete(&ctx->done);
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}
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ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
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static ssize_t __cifs_readv(
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struct kiocb *iocb, struct iov_iter *to, bool direct)
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{
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struct file *file = iocb->ki_filp;
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ssize_t rc;
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size_t len;
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ssize_t total_read = 0;
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loff_t offset = iocb->ki_pos;
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struct file *file = iocb->ki_filp;
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struct cifs_sb_info *cifs_sb;
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struct cifs_tcon *tcon;
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struct cifsFileInfo *cfile;
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struct cifs_tcon *tcon;
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ssize_t rc, total_read = 0;
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loff_t offset = iocb->ki_pos;
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struct cifs_aio_ctx *ctx;
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/*
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* iov_iter_get_pages_alloc() doesn't work with ITER_KVEC,
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* fall back to data copy read path
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* this could be improved by getting pages directly in ITER_KVEC
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*/
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if (direct && to->type & ITER_KVEC) {
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cifs_dbg(FYI, "use non-direct cifs_user_readv for kvec I/O\n");
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direct = false;
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}
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len = iov_iter_count(to);
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if (!len)
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return 0;
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@ -3319,13 +3450,19 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
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if (iter_is_iovec(to))
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ctx->should_dirty = true;
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if (direct) {
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ctx->pos = offset;
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ctx->direct_io = true;
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ctx->iter = *to;
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ctx->len = len;
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} else {
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rc = setup_aio_ctx_iter(ctx, to, READ);
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if (rc) {
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kref_put(&ctx->refcount, cifs_aio_ctx_release);
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return rc;
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}
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len = ctx->len;
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}
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/* grab a lock here due to read response handlers can access ctx */
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mutex_lock(&ctx->aio_mutex);
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@ -3368,6 +3505,16 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
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return rc;
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}
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ssize_t cifs_direct_readv(struct kiocb *iocb, struct iov_iter *to)
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{
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return __cifs_readv(iocb, to, true);
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}
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ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
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{
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return __cifs_readv(iocb, to, false);
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}
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ssize_t
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cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to)
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{
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