diff options
| -rw-r--r-- | mm/shmem.c | 105 |
1 files changed, 72 insertions, 33 deletions
@@ -89,7 +89,8 @@ enum sgp_type { SGP_READ, /* don't exceed i_size, don't allocate page */ SGP_CACHE, /* don't exceed i_size, may allocate page */ SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ - SGP_WRITE, /* may exceed i_size, may allocate page */ + SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */ + SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */ }; #ifdef CONFIG_TMPFS @@ -427,8 +428,10 @@ void shmem_unlock_mapping(struct address_space *mapping) /* * Remove range of pages and swap entries from radix tree, and free them. + * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate. */ -void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) +static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, + bool unfalloc) { struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info = SHMEM_I(inode); @@ -462,6 +465,8 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) break; if (radix_tree_exceptional_entry(page)) { + if (unfalloc) + continue; nr_swaps_freed += !shmem_free_swap(mapping, index, page); continue; @@ -469,9 +474,11 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) if (!trylock_page(page)) continue; - if (page->mapping == mapping) { - VM_BUG_ON(PageWriteback(page)); - truncate_inode_page(mapping, page); + if (!unfalloc || !PageUptodate(page)) { + if (page->mapping == mapping) { + VM_BUG_ON(PageWriteback(page)); + truncate_inode_page(mapping, page); + } } unlock_page(page); } @@ -517,12 +524,12 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) min(end - index, (pgoff_t)PAGEVEC_SIZE), pvec.pages, indices); if (!pvec.nr) { - if (index == start) + if (index == start || unfalloc) break; index = start; continue; } - if (index == start && indices[0] >= end) { + if ((index == start || unfalloc) && indices[0] >= end) { shmem_deswap_pagevec(&pvec); pagevec_release(&pvec); break; @@ -536,15 +543,19 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) break; if (radix_tree_exceptional_entry(page)) { + if (unfalloc) + continue; nr_swaps_freed += !shmem_free_swap(mapping, index, page); continue; } lock_page(page); - if (page->mapping == mapping) { - VM_BUG_ON(PageWriteback(page)); - truncate_inode_page(mapping, page); + if (!unfalloc || !PageUptodate(page)) { + if (page->mapping == mapping) { + VM_BUG_ON(PageWriteback(page)); + truncate_inode_page(mapping, page); + } } unlock_page(page); } @@ -558,7 +569,11 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) info->swapped -= nr_swaps_freed; shmem_recalc_inode(inode); spin_unlock(&info->lock); +} +void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) +{ + shmem_undo_range(inode, lstart, lend, false); inode->i_ctime = inode->i_mtime = CURRENT_TIME; } EXPORT_SYMBOL_GPL(shmem_truncate_range); @@ -771,6 +786,18 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ goto redirty; } + + /* + * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC + * value into swapfile.c, the only way we can correctly account for a + * fallocated page arriving here is now to initialize it and write it. + */ + if (!PageUptodate(page)) { + clear_highpage(page); + flush_dcache_page(page); + SetPageUptodate(page); + } + swap = get_swap_page(); if (!swap.val) goto redirty; @@ -994,6 +1021,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, swp_entry_t swap; int error; int once = 0; + int alloced = 0; if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT)) return -EFBIG; @@ -1005,19 +1033,21 @@ repeat: page = NULL; } - if (sgp != SGP_WRITE && + if (sgp != SGP_WRITE && sgp != SGP_FALLOC && ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { error = -EINVAL; goto failed; } + /* fallocated page? */ + if (page && !PageUptodate(page)) { + if (sgp != SGP_READ) + goto clear; + unlock_page(page); + page_cache_release(page); + page = NULL; + } if (page || (sgp == SGP_READ && !swap.val)) { - /* - * Once we can get the page lock, it must be uptodate: - * if there were an error in reading back from swap, - * the page would not be inserted into the filecache. - */ - BUG_ON(page && !PageUptodate(page)); *pagep = page; return 0; } @@ -1114,9 +1144,18 @@ repeat: inode->i_blocks += BLOCKS_PER_PAGE; shmem_recalc_inode(inode); spin_unlock(&info->lock); + alloced = true; /* - * Let SGP_WRITE caller clear ends if write does not fill page + * Let SGP_FALLOC use the SGP_WRITE optimization on a new page. + */ + if (sgp == SGP_FALLOC) + sgp = SGP_WRITE; +clear: + /* + * Let SGP_WRITE caller clear ends if write does not fill page; + * but SGP_FALLOC on a page fallocated earlier must initialize + * it now, lest undo on failure cancel our earlier guarantee. */ if (sgp != SGP_WRITE) { clear_highpage(page); @@ -1128,10 +1167,13 @@ repeat: } /* Perhaps the file has been truncated since we checked */ - if (sgp != SGP_WRITE && + if (sgp != SGP_WRITE && sgp != SGP_FALLOC && ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { error = -EINVAL; - goto trunc; + if (alloced) + goto trunc; + else + goto failed; } *pagep = page; return 0; @@ -1140,6 +1182,7 @@ repeat: * Error recovery. */ trunc: + info = SHMEM_I(inode); ClearPageDirty(page); delete_from_page_cache(page); spin_lock(&info->lock); @@ -1147,6 +1190,7 @@ trunc: inode->i_blocks -= BLOCKS_PER_PAGE; spin_unlock(&info->lock); decused: + sbinfo = SHMEM_SB(inode->i_sb); if (sbinfo->max_blocks) percpu_counter_add(&sbinfo->used_blocks, -1); unacct: @@ -1645,25 +1689,20 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset, if (signal_pending(current)) error = -EINTR; else - error = shmem_getpage(inode, index, &page, SGP_WRITE, + error = shmem_getpage(inode, index, &page, SGP_FALLOC, NULL); if (error) { - /* - * We really ought to free what we allocated so far, - * but it would be wrong to free pages allocated - * earlier, or already now in use: i_mutex does not - * exclude all cases. We do not know what to free. - */ + /* Remove the !PageUptodate pages we added */ + shmem_undo_range(inode, + (loff_t)start << PAGE_CACHE_SHIFT, + (loff_t)index << PAGE_CACHE_SHIFT, true); goto ctime; } - if (!PageUptodate(page)) { - clear_highpage(page); - flush_dcache_page(page); - SetPageUptodate(page); - } /* - * set_page_dirty so that memory pressure will swap rather + * If !PageUptodate, leave it that way so that freeable pages + * can be recognized if we need to rollback on error later. + * But set_page_dirty so that memory pressure will swap rather * than free the pages we are allocating (and SGP_CACHE pages * might still be clean: we now need to mark those dirty too). */ |
