diff options
Diffstat (limited to 'mm/shmem.c')
| -rw-r--r-- | mm/shmem.c | 35 |
1 files changed, 22 insertions, 13 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 529c9ad3e926..f3e8de8ff75c 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2426,7 +2426,7 @@ static int shmem_initxattrs(struct inode *, const struct xattr *, void *); static int shmem_write_begin(struct file *file, struct address_space *mapping, - loff_t pos, unsigned len, unsigned flags, + loff_t pos, unsigned len, struct page **pagep, void **fsdata) { struct inode *inode = mapping->host; @@ -2513,7 +2513,6 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) pgoff_t end_index; unsigned long nr, ret; loff_t i_size = i_size_read(inode); - bool got_page; end_index = i_size >> PAGE_SHIFT; if (index > end_index) @@ -2570,24 +2569,34 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) */ if (!offset) mark_page_accessed(page); - got_page = true; + /* + * Ok, we have the page, and it's up-to-date, so + * now we can copy it to user space... + */ + ret = copy_page_to_iter(page, offset, nr, to); + put_page(page); + + } else if (iter_is_iovec(to)) { + /* + * Copy to user tends to be so well optimized, but + * clear_user() not so much, that it is noticeably + * faster to copy the zero page instead of clearing. + */ + ret = copy_page_to_iter(ZERO_PAGE(0), offset, nr, to); } else { - page = ZERO_PAGE(0); - got_page = false; + /* + * But submitting the same page twice in a row to + * splice() - or others? - can result in confusion: + * so don't attempt that optimization on pipes etc. + */ + ret = iov_iter_zero(nr, to); } - /* - * Ok, we have the page, and it's up-to-date, so - * now we can copy it to user space... - */ - ret = copy_page_to_iter(page, offset, nr, to); retval += ret; offset += ret; index += offset >> PAGE_SHIFT; offset &= ~PAGE_MASK; - if (got_page) - put_page(page); if (!iov_iter_count(to)) break; if (ret < nr) { @@ -4153,7 +4162,7 @@ int shmem_zero_setup(struct vm_area_struct *vma) * * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", * with any new page allocations done using the specified allocation flags. - * But read_cache_page_gfp() uses the ->readpage() method: which does not + * But read_cache_page_gfp() uses the ->read_folio() method: which does not * suit tmpfs, since it may have pages in swapcache, and needs to find those * for itself; although drivers/gpu/drm i915 and ttm rely upon this support. * |