cifs: turn the pages list in cifs_readdata into an array

We'll need an array to put into a smb_rqst, so convert this into an array
instead of (ab)using the lru list_head.

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

2 files changed, 52 insertions, 38 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 737289b50ca5..b70863ebedf2 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -977,12 +977,13 @@ struct cifs_readdata {
         unsigned int                    bytes;
         pid_t                           pid;
         int                             result;
-        struct list_head                pages;
         struct work_struct              work;
         int (*marshal_iov) (struct cifs_readdata *rdata,
                             unsigned int remaining);
         unsigned int                    nr_iov;
         struct kvec                     *iov;
+        unsigned int                    nr_pages;
+        struct page                     *pages[];
 };
 
 struct cifs_writedata;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 61b7c834069f..6eaf48270c97 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2419,13 +2419,13 @@ cifs_readdata_alloc(unsigned int nr_pages, work_func_t complete)
         if (!iov)
                 return (struct cifs_readdata *)iov;
 
-        rdata = kzalloc(sizeof(*rdata), GFP_KERNEL);
+        rdata = kzalloc(sizeof(*rdata) + (sizeof(struct page *) * nr_pages),
+                        GFP_KERNEL);
         if (rdata != NULL) {
                 kref_init(&rdata->refcount);
                 INIT_LIST_HEAD(&rdata->list);
                 init_completion(&rdata->done);
                 INIT_WORK(&rdata->work, complete);
-                INIT_LIST_HEAD(&rdata->pages);
                 rdata->iov = iov;
         } else {
                 kfree(iov);
@@ -2448,25 +2448,25 @@ cifs_readdata_release(struct kref *refcount)
 }
 
 static int
-cifs_read_allocate_pages(struct list_head *list, unsigned int npages)
+cifs_read_allocate_pages(struct cifs_readdata *rdata, unsigned int nr_pages)
 {
         int rc = 0;
-        struct page *page, *tpage;
+        struct page *page;
         unsigned int i;
 
-        for (i = 0; i < npages; i++) {
+        for (i = 0; i < nr_pages; i++) {
                 page = alloc_page(GFP_KERNEL|__GFP_HIGHMEM);
                 if (!page) {
                         rc = -ENOMEM;
                         break;
                 }
-                list_add(&page->lru, list);
+                rdata->pages[i] = page;
         }
 
         if (rc) {
-                list_for_each_entry_safe(page, tpage, list, lru) {
-                        list_del(&page->lru);
-                        put_page(page);
+                for (i = 0; i < nr_pages; i++) {
+                        put_page(rdata->pages[i]);
+                        rdata->pages[i] = NULL;
                 }
         }
         return rc;
@@ -2475,13 +2475,13 @@ cifs_read_allocate_pages(struct list_head *list, unsigned int npages)
 static void
 cifs_uncached_readdata_release(struct kref *refcount)
 {
-        struct page *page, *tpage;
         struct cifs_readdata *rdata = container_of(refcount,
                                         struct cifs_readdata, refcount);
+        unsigned int i;
 
-        list_for_each_entry_safe(page, tpage, &rdata->pages, lru) {
-                list_del(&page->lru);
-                put_page(page);
+        for (i = 0; i < rdata->nr_pages; i++) {
+                put_page(rdata->pages[i]);
+                rdata->pages[i] = NULL;
         }
         cifs_readdata_release(refcount);
 }
@@ -2525,17 +2525,18 @@ cifs_readdata_to_iov(struct cifs_readdata *rdata, const struct iovec *iov,
         int rc = 0;
         struct iov_iter ii;
         size_t pos = rdata->offset - offset;
-        struct page *page, *tpage;
         ssize_t remaining = rdata->bytes;
         unsigned char *pdata;
+        unsigned int i;
 
         /* set up iov_iter and advance to the correct offset */
         iov_iter_init(&ii, iov, nr_segs, iov_length(iov, nr_segs), 0);
         iov_iter_advance(&ii, pos);
 
         *copied = 0;
-        list_for_each_entry_safe(page, tpage, &rdata->pages, lru) {
+        for (i = 0; i < rdata->nr_pages; i++) {
                 ssize_t copy;
+                struct page *page = rdata->pages[i];
 
                 /* copy a whole page or whatever's left */
                 copy = min_t(ssize_t, remaining, PAGE_SIZE);
@@ -2555,9 +2556,6 @@ cifs_readdata_to_iov(struct cifs_readdata *rdata, const struct iovec *iov,
                                 iov_iter_advance(&ii, copy);
                         }
                 }
-
-                list_del(&page->lru);
-                put_page(page);
         }
 
         return rc;
@@ -2568,13 +2566,12 @@ 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) {
-                struct page *page;
-
-                list_for_each_entry(page, &rdata->pages, lru)
-                        kunmap(page);
+                for (i = 0; i < rdata->nr_pages; i++)
+                        kunmap(rdata->pages[i]);
         }
 
         complete(&rdata->done);
@@ -2586,10 +2583,13 @@ cifs_uncached_read_marshal_iov(struct cifs_readdata *rdata,
                                 unsigned int remaining)
 {
         int len = 0;
-        struct page *page, *tpage;
+        unsigned int i;
+        unsigned int nr_pages = rdata->nr_pages;
 
         rdata->nr_iov = 1;
-        list_for_each_entry_safe(page, tpage, &rdata->pages, lru) {
+        for (i = 0; i < nr_pages; i++) {
+                struct page *page = rdata->pages[i];
+
                 if (remaining >= PAGE_SIZE) {
                         /* enough data to fill the page */
                         rdata->iov[rdata->nr_iov].iov_base = kmap(page);
@@ -2616,7 +2616,8 @@ cifs_uncached_read_marshal_iov(struct cifs_readdata *rdata,
                         remaining = 0;
                 } else {
                         /* no need to hold page hostage */
-                        list_del(&page->lru);
+                        rdata->pages[i] = NULL;
+                        rdata->nr_pages--;
                         put_page(page);
                 }
         }
@@ -2675,11 +2676,12 @@ cifs_iovec_read(struct file *file, const struct iovec *iov,
                         goto error;
                 }
 
-                rc = cifs_read_allocate_pages(&rdata->pages, npages);
+                rc = cifs_read_allocate_pages(rdata, npages);
                 if (rc)
                         goto error;
 
                 rdata->cfile = cifsFileInfo_get(open_file);
+                rdata->nr_pages = npages;
                 rdata->offset = offset;
                 rdata->bytes = cur_len;
                 rdata->pid = pid;
@@ -2923,12 +2925,13 @@ int cifs_file_mmap(struct file *file, struct vm_area_struct *vma)
 static void
 cifs_readv_complete(struct work_struct *work)
 {
+        unsigned int i;
         struct cifs_readdata *rdata = container_of(work,
                                                 struct cifs_readdata, work);
-        struct page *page, *tpage;
 
-        list_for_each_entry_safe(page, tpage, &rdata->pages, lru) {
-                list_del(&page->lru);
+        for (i = 0; i < rdata->nr_pages; i++) {
+                struct page *page = rdata->pages[i];
+
                 lru_cache_add_file(page);
 
                 if (rdata->result == 0) {
@@ -2943,6 +2946,7 @@ cifs_readv_complete(struct work_struct *work)
                         cifs_readpage_to_fscache(rdata->mapping->host, page);
 
                 page_cache_release(page);
+                rdata->pages[i] = NULL;
         }
         kref_put(&rdata->refcount, cifs_readdata_release);
 }
@@ -2951,9 +2955,10 @@ static int
 cifs_readpages_marshal_iov(struct cifs_readdata *rdata, unsigned int remaining)
 {
         int len = 0;
-        struct page *page, *tpage;
+        unsigned int i;
         u64 eof;
         pgoff_t eof_index;
+        unsigned int nr_pages = rdata->nr_pages;
 
         /* determine the eof that the server (probably) has */
         eof = CIFS_I(rdata->mapping->host)->server_eof;
@@ -2961,7 +2966,9 @@ cifs_readpages_marshal_iov(struct cifs_readdata *rdata, unsigned int remaining)
         cFYI(1, "eof=%llu eof_index=%lu", eof, eof_index);
 
         rdata->nr_iov = 1;
-        list_for_each_entry_safe(page, tpage, &rdata->pages, lru) {
+        for (i = 0; i < nr_pages; i++) {
+                struct page *page = rdata->pages[i];
+
                 if (remaining >= PAGE_CACHE_SIZE) {
                         /* enough data to fill the page */
                         rdata->iov[rdata->nr_iov].iov_base = kmap(page);
@@ -2996,18 +3003,20 @@ cifs_readpages_marshal_iov(struct cifs_readdata *rdata, unsigned int remaining)
                          * fill them until the writes are flushed.
                          */
                         zero_user(page, 0, PAGE_CACHE_SIZE);
-                        list_del(&page->lru);
                         lru_cache_add_file(page);
                         flush_dcache_page(page);
                         SetPageUptodate(page);
                         unlock_page(page);
                         page_cache_release(page);
+                        rdata->pages[i] = NULL;
+                        rdata->nr_pages--;
                 } else {
                         /* no need to hold page hostage */
-                        list_del(&page->lru);
                         lru_cache_add_file(page);
                         unlock_page(page);
                         page_cache_release(page);
+                        rdata->pages[i] = NULL;
+                        rdata->nr_pages--;
                 }
         }
 
@@ -3065,6 +3074,7 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
          * the rdata->pages, then we want them in increasing order.
          */
         while (!list_empty(page_list)) {
+                unsigned int i;
                 unsigned int bytes = PAGE_CACHE_SIZE;
                 unsigned int expected_index;
                 unsigned int nr_pages = 1;
@@ -3135,13 +3145,16 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                 rdata->bytes = bytes;
                 rdata->pid = pid;
                 rdata->marshal_iov = cifs_readpages_marshal_iov;
-                list_splice_init(&tmplist, &rdata->pages);
+
+                list_for_each_entry_safe(page, tpage, &tmplist, lru) {
+                        list_del(&page->lru);
+                        rdata->pages[rdata->nr_pages++] = page;
+                }
 
                 rc = cifs_retry_async_readv(rdata);
                 if (rc != 0) {
-                        list_for_each_entry_safe(page, tpage, &rdata->pages,
-                                                 lru) {
-                                list_del(&page->lru);
+                        for (i = 0; i < rdata->nr_pages; i++) {
+                                page = rdata->pages[i];
                                 lru_cache_add_file(page);
                                 unlock_page(page);
                                 page_cache_release(page);