diff options
| -rw-r--r-- | fs/afs/internal.h | 24 | ||||
| -rw-r--r-- | fs/afs/write.c | 5 |
2 files changed, 20 insertions, 9 deletions
diff --git a/fs/afs/internal.h b/fs/afs/internal.h index b0fce1f75397..14d5d75f4b6e 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -861,7 +861,8 @@ struct afs_vnode_cache_aux { /* * We use page->private to hold the amount of the page that we've written to, * splitting the field into two parts. However, we need to represent a range - * 0...PAGE_SIZE inclusive, so we can't support 64K pages on a 32-bit system. + * 0...PAGE_SIZE, so we reduce the resolution if the size of the page + * exceeds what we can encode. */ #ifdef CONFIG_64BIT #define __AFS_PAGE_PRIV_MASK 0x7fffffffUL @@ -873,19 +874,34 @@ struct afs_vnode_cache_aux { #define __AFS_PAGE_PRIV_MMAPPED 0x8000UL #endif +static inline unsigned int afs_page_dirty_resolution(void) +{ + int shift = PAGE_SHIFT - (__AFS_PAGE_PRIV_SHIFT - 1); + return (shift > 0) ? shift : 0; +} + static inline size_t afs_page_dirty_from(unsigned long priv) { - return priv & __AFS_PAGE_PRIV_MASK; + unsigned long x = priv & __AFS_PAGE_PRIV_MASK; + + /* The lower bound is inclusive */ + return x << afs_page_dirty_resolution(); } static inline size_t afs_page_dirty_to(unsigned long priv) { - return ((priv >> __AFS_PAGE_PRIV_SHIFT) & __AFS_PAGE_PRIV_MASK) + 1; + unsigned long x = (priv >> __AFS_PAGE_PRIV_SHIFT) & __AFS_PAGE_PRIV_MASK; + + /* The upper bound is immediately beyond the region */ + return (x + 1) << afs_page_dirty_resolution(); } static inline unsigned long afs_page_dirty(size_t from, size_t to) { - return ((unsigned long)(to - 1) << __AFS_PAGE_PRIV_SHIFT) | from; + unsigned int res = afs_page_dirty_resolution(); + from >>= res; + to = (to - 1) >> res; + return (to << __AFS_PAGE_PRIV_SHIFT) | from; } static inline unsigned long afs_page_dirty_mmapped(unsigned long priv) diff --git a/fs/afs/write.c b/fs/afs/write.c index a2511e3ad2cc..50371207f327 100644 --- a/fs/afs/write.c +++ b/fs/afs/write.c @@ -90,11 +90,6 @@ int afs_write_begin(struct file *file, struct address_space *mapping, _enter("{%llx:%llu},{%lx},%u,%u", vnode->fid.vid, vnode->fid.vnode, index, from, to); - /* We want to store information about how much of a page is altered in - * page->private. - */ - BUILD_BUG_ON(PAGE_SIZE - 1 > __AFS_PAGE_PRIV_MASK && sizeof(page->private) < 8); - page = grab_cache_page_write_begin(mapping, index, flags); if (!page) return -ENOMEM; |