cifs: convert async read code to use pages array without kmapping

Replace the "marshal_iov" function with a "read_into_pages" function.
That function will copy the read data off the socket and into the
pages array, kmapping and reading pages one at a time.

Signed-off-by: Jeff Layton <jlayton@redhat.com>

4 files changed, 80 insertions, 81 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index b70863ebedf..93e16200b2e 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -978,8 +978,11 @@ struct cifs_readdata {
         pid_t                           pid;
         int                             result;
         struct work_struct              work;
-        int (*marshal_iov) (struct cifs_readdata *rdata,
-                            unsigned int remaining);
+        int (*read_into_pages)(struct TCP_Server_Info *server,
+                                struct cifs_readdata *rdata,
+                                unsigned int len);
+        unsigned int                    pagesz;
+        unsigned int                    tailsz;
         unsigned int                    nr_iov;
         struct kvec                     *iov;
         unsigned int                    nr_pages;
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index a110e078422..5d7bd757dcf 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1496,6 +1496,7 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
         /* set up first iov for signature check */
         rdata->iov[0].iov_base = buf;
         rdata->iov[0].iov_len = server->total_read;
+        rdata->nr_iov = 1;
         cFYI(1, "0: iov_base=%p iov_len=%zu",
                 rdata->iov[0].iov_base, rdata->iov[0].iov_len);
 
@@ -1507,23 +1508,11 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
                 return cifs_readv_discard(server, mid);
         }
 
-        /* marshal up the page array */
-        cifs_kmap_lock();
-        len = rdata->marshal_iov(rdata, data_len);
-        cifs_kmap_unlock();
-        data_len -= len;
-
-        /* issue the read if we have any iovecs left to fill */
-        if (rdata->nr_iov > 1) {
-                length = cifs_readv_from_socket(server, &rdata->iov[1],
-                                                rdata->nr_iov - 1, len);
-                if (length < 0)
-                        return length;
-                server->total_read += length;
-        } else {
-                length = 0;
-        }
+        length = rdata->read_into_pages(server, rdata, data_len);
+        if (length < 0)
+                return length;
 
+        server->total_read += length;
         rdata->bytes = length;
 
         cFYI(1, "total_read=%u buflen=%u remaining=%u", server->total_read,
@@ -1544,7 +1533,11 @@ cifs_readv_callback(struct mid_q_entry *mid)
         struct cifs_tcon *tcon = tlink_tcon(rdata->cfile->tlink);
         struct TCP_Server_Info *server = tcon->ses->server;
         struct smb_rqst rqst = { .rq_iov = rdata->iov,
-                                 .rq_nvec = rdata->nr_iov };
+                                 .rq_nvec = rdata->nr_iov,
+                                 .rq_pages = rdata->pages,
+                                 .rq_npages = rdata->nr_pages,
+                                 .rq_pagesz = rdata->pagesz,
+                                 .rq_tailsz = rdata->tailsz };
 
         cFYI(1, "%s: mid=%llu state=%d result=%d bytes=%u", __func__,
                 mid->mid, mid->mid_state, rdata->result, rdata->bytes);
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 6eaf48270c9..f3f1b1098a6 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2566,63 +2566,57 @@ cifs_uncached_readv_complete(struct work_struct *work)
 {
         struct cifs_readdata *rdata = container_of(work,
                                                 struct cifs_readdata, work);
-        unsigned int i;
-
-        /* if the result is non-zero then the pages weren't kmapped */
-        if (rdata->result == 0) {
-                for (i = 0; i < rdata->nr_pages; i++)
-                        kunmap(rdata->pages[i]);
-        }
 
         complete(&rdata->done);
         kref_put(&rdata->refcount, cifs_uncached_readdata_release);
 }
 
 static int
-cifs_uncached_read_marshal_iov(struct cifs_readdata *rdata,
-                                unsigned int remaining)
+cifs_uncached_read_into_pages(struct TCP_Server_Info *server,
+                        struct cifs_readdata *rdata, unsigned int len)
 {
-        int len = 0;
+        int total_read = 0, result = 0;
         unsigned int i;
         unsigned int nr_pages = rdata->nr_pages;
+        struct kvec iov;
 
-        rdata->nr_iov = 1;
+        rdata->tailsz = PAGE_SIZE;
         for (i = 0; i < nr_pages; i++) {
                 struct page *page = rdata->pages[i];
 
-                if (remaining >= PAGE_SIZE) {
+                if (len >= PAGE_SIZE) {
                         /* enough data to fill the page */
-                        rdata->iov[rdata->nr_iov].iov_base = kmap(page);
-                        rdata->iov[rdata->nr_iov].iov_len = PAGE_SIZE;
-                        cFYI(1, "%u: idx=%lu iov_base=%p iov_len=%zu",
-                                rdata->nr_iov, page->index,
-                                rdata->iov[rdata->nr_iov].iov_base,
-                                rdata->iov[rdata->nr_iov].iov_len);
-                        ++rdata->nr_iov;
-                        len += PAGE_SIZE;
-                        remaining -= PAGE_SIZE;
-                } else if (remaining > 0) {
+                        iov.iov_base = kmap(page);
+                        iov.iov_len = PAGE_SIZE;
+                        cFYI(1, "%u: iov_base=%p iov_len=%zu",
+                                i, iov.iov_base, iov.iov_len);
+                        len -= PAGE_SIZE;
+                } else if (len > 0) {
                         /* enough for partial page, fill and zero the rest */
-                        rdata->iov[rdata->nr_iov].iov_base = kmap(page);
-                        rdata->iov[rdata->nr_iov].iov_len = remaining;
-                        cFYI(1, "%u: idx=%lu iov_base=%p iov_len=%zu",
-                                rdata->nr_iov, page->index,
-                                rdata->iov[rdata->nr_iov].iov_base,
-                                rdata->iov[rdata->nr_iov].iov_len);
-                        memset(rdata->iov[rdata->nr_iov].iov_base + remaining,
-                                '\0', PAGE_SIZE - remaining);
-                        ++rdata->nr_iov;
-                        len += remaining;
-                        remaining = 0;
+                        iov.iov_base = kmap(page);
+                        iov.iov_len = len;
+                        cFYI(1, "%u: iov_base=%p iov_len=%zu",
+                                i, iov.iov_base, iov.iov_len);
+                        memset(iov.iov_base + len, '\0', PAGE_SIZE - len);
+                        rdata->tailsz = len;
+                        len = 0;
                 } else {
                         /* no need to hold page hostage */
                         rdata->pages[i] = NULL;
                         rdata->nr_pages--;
                         put_page(page);
+                        continue;
                 }
+
+                result = cifs_readv_from_socket(server, &iov, 1, iov.iov_len);
+                kunmap(page);
+                if (result < 0)
+                        break;
+
+                total_read += result;
         }
 
-        return len;
+        return total_read > 0 ? total_read : result;
 }
 
 static ssize_t
@@ -2685,7 +2679,8 @@ cifs_iovec_read(struct file *file, const struct iovec *iov,
                 rdata->offset = offset;
                 rdata->bytes = cur_len;
                 rdata->pid = pid;
-                rdata->marshal_iov = cifs_uncached_read_marshal_iov;
+                rdata->pagesz = PAGE_SIZE;
+                rdata->read_into_pages = cifs_uncached_read_into_pages;
 
                 rc = cifs_retry_async_readv(rdata);
 error:
@@ -2935,7 +2930,6 @@ cifs_readv_complete(struct work_struct *work)
                 lru_cache_add_file(page);
 
                 if (rdata->result == 0) {
-                        kunmap(page);
                         flush_dcache_page(page);
                         SetPageUptodate(page);
                 }
@@ -2952,47 +2946,42 @@ cifs_readv_complete(struct work_struct *work)
 }
 
 static int
-cifs_readpages_marshal_iov(struct cifs_readdata *rdata, unsigned int remaining)
+cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
+                        struct cifs_readdata *rdata, unsigned int len)
 {
-        int len = 0;
+        int total_read = 0, result = 0;
         unsigned int i;
         u64 eof;
         pgoff_t eof_index;
         unsigned int nr_pages = rdata->nr_pages;
+        struct kvec iov;
 
         /* determine the eof that the server (probably) has */
         eof = CIFS_I(rdata->mapping->host)->server_eof;
         eof_index = eof ? (eof - 1) >> PAGE_CACHE_SHIFT : 0;
         cFYI(1, "eof=%llu eof_index=%lu", eof, eof_index);
 
-        rdata->nr_iov = 1;
+        rdata->tailsz = PAGE_CACHE_SIZE;
         for (i = 0; i < nr_pages; i++) {
                 struct page *page = rdata->pages[i];
 
-                if (remaining >= PAGE_CACHE_SIZE) {
+                if (len >= PAGE_CACHE_SIZE) {
                         /* enough data to fill the page */
-                        rdata->iov[rdata->nr_iov].iov_base = kmap(page);
-                        rdata->iov[rdata->nr_iov].iov_len = PAGE_CACHE_SIZE;
+                        iov.iov_base = kmap(page);
+                        iov.iov_len = PAGE_CACHE_SIZE;
                         cFYI(1, "%u: idx=%lu iov_base=%p iov_len=%zu",
-                                rdata->nr_iov, page->index,
-                                rdata->iov[rdata->nr_iov].iov_base,
-                                rdata->iov[rdata->nr_iov].iov_len);
-                        ++rdata->nr_iov;
-                        len += PAGE_CACHE_SIZE;
-                        remaining -= PAGE_CACHE_SIZE;
-                } else if (remaining > 0) {
+                                i, page->index, iov.iov_base, iov.iov_len);
+                        len -= PAGE_CACHE_SIZE;
+                } else if (len > 0) {
                         /* enough for partial page, fill and zero the rest */
-                        rdata->iov[rdata->nr_iov].iov_base = kmap(page);
-                        rdata->iov[rdata->nr_iov].iov_len = remaining;
+                        iov.iov_base = kmap(page);
+                        iov.iov_len = len;
                         cFYI(1, "%u: idx=%lu iov_base=%p iov_len=%zu",
-                                rdata->nr_iov, page->index,
-                                rdata->iov[rdata->nr_iov].iov_base,
-                                rdata->iov[rdata->nr_iov].iov_len);
-                        memset(rdata->iov[rdata->nr_iov].iov_base + remaining,
-                                '\0', PAGE_CACHE_SIZE - remaining);
-                        ++rdata->nr_iov;
-                        len += remaining;
-                        remaining = 0;
+                                i, page->index, iov.iov_base, iov.iov_len);
+                        memset(iov.iov_base + len,
+                                '\0', PAGE_CACHE_SIZE - len);
+                        rdata->tailsz = len;
+                        len = 0;
                 } else if (page->index > eof_index) {
                         /*
                          * The VFS will not try to do readahead past the
@@ -3010,6 +2999,7 @@ cifs_readpages_marshal_iov(struct cifs_readdata *rdata, unsigned int remaining)
                         page_cache_release(page);
                         rdata->pages[i] = NULL;
                         rdata->nr_pages--;
+                        continue;
                 } else {
                         /* no need to hold page hostage */
                         lru_cache_add_file(page);
@@ -3017,10 +3007,18 @@ cifs_readpages_marshal_iov(struct cifs_readdata *rdata, unsigned int remaining)
                         page_cache_release(page);
                         rdata->pages[i] = NULL;
                         rdata->nr_pages--;
+                        continue;
                 }
+
+                result = cifs_readv_from_socket(server, &iov, 1, iov.iov_len);
+                kunmap(page);
+                if (result < 0)
+                        break;
+
+                total_read += result;
         }
 
-        return len;
+        return total_read > 0 ? total_read : result;
 }
 
 static int cifs_readpages(struct file *file, struct address_space *mapping,
@@ -3144,7 +3142,8 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                 rdata->offset = offset;
                 rdata->bytes = bytes;
                 rdata->pid = pid;
-                rdata->marshal_iov = cifs_readpages_marshal_iov;
+                rdata->pagesz = PAGE_CACHE_SIZE;
+                rdata->read_into_pages = cifs_readpages_read_into_pages;
 
                 list_for_each_entry_safe(page, tpage, &tmplist, lru) {
                         list_del(&page->lru);
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 68023d23702..e3efa47cd6e 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -1300,7 +1300,11 @@ smb2_readv_callback(struct mid_q_entry *mid)
         struct smb2_hdr *buf = (struct smb2_hdr *)rdata->iov[0].iov_base;
         unsigned int credits_received = 1;
         struct smb_rqst rqst = { .rq_iov = rdata->iov,
-                                 .rq_nvec = rdata->nr_iov };
+                                 .rq_nvec = 1,
+                                 .rq_pages = rdata->pages,
+                                 .rq_npages = rdata->nr_pages,
+                                 .rq_pagesz = rdata->pagesz,
+                                 .rq_tailsz = rdata->tailsz };
 
         cFYI(1, "%s: mid=%llu state=%d result=%d bytes=%u", __func__,
                 mid->mid, mid->mid_state, rdata->result, rdata->bytes);