diff options
| -rw-r--r-- | mm/shmem.c | 237 |
1 files changed, 108 insertions, 129 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 8f8534f35476..bf6e9c11d859 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1246,41 +1246,47 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t idx, struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info = SHMEM_I(inode); struct shmem_sb_info *sbinfo; - struct page *filepage; - struct page *swappage; + struct page *page; struct page *prealloc_page = NULL; swp_entry_t *entry; swp_entry_t swap; int error; + int ret; if (idx >= SHMEM_MAX_INDEX) return -EFBIG; repeat: - filepage = find_lock_page(mapping, idx); - if (filepage && PageUptodate(filepage)) - goto done; - if (!filepage) { + page = find_lock_page(mapping, idx); + if (page) { /* - * Try to preload while we can wait, to not make a habit of - * draining atomic reserves; but don't latch on to this cpu. + * 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. */ - error = radix_tree_preload(gfp & GFP_RECLAIM_MASK); - if (error) - goto failed; - radix_tree_preload_end(); - if (sgp != SGP_READ && !prealloc_page) { - prealloc_page = shmem_alloc_page(gfp, info, idx); - if (prealloc_page) { - SetPageSwapBacked(prealloc_page); - if (mem_cgroup_cache_charge(prealloc_page, - current->mm, GFP_KERNEL)) { - page_cache_release(prealloc_page); - prealloc_page = NULL; - } + BUG_ON(!PageUptodate(page)); + goto done; + } + + /* + * Try to preload while we can wait, to not make a habit of + * draining atomic reserves; but don't latch on to this cpu. + */ + error = radix_tree_preload(gfp & GFP_RECLAIM_MASK); + if (error) + goto out; + radix_tree_preload_end(); + + if (sgp != SGP_READ && !prealloc_page) { + prealloc_page = shmem_alloc_page(gfp, info, idx); + if (prealloc_page) { + SetPageSwapBacked(prealloc_page); + if (mem_cgroup_cache_charge(prealloc_page, + current->mm, GFP_KERNEL)) { + page_cache_release(prealloc_page); + prealloc_page = NULL; } } } - error = 0; spin_lock(&info->lock); shmem_recalc_inode(inode); @@ -1288,21 +1294,21 @@ repeat: if (IS_ERR(entry)) { spin_unlock(&info->lock); error = PTR_ERR(entry); - goto failed; + goto out; } swap = *entry; if (swap.val) { /* Look it up and read it in.. */ - swappage = lookup_swap_cache(swap); - if (!swappage) { + page = lookup_swap_cache(swap); + if (!page) { shmem_swp_unmap(entry); spin_unlock(&info->lock); /* here we actually do the io */ if (fault_type) *fault_type |= VM_FAULT_MAJOR; - swappage = shmem_swapin(swap, gfp, info, idx); - if (!swappage) { + page = shmem_swapin(swap, gfp, info, idx); + if (!page) { spin_lock(&info->lock); entry = shmem_swp_alloc(info, idx, sgp, gfp); if (IS_ERR(entry)) @@ -1314,62 +1320,42 @@ repeat: } spin_unlock(&info->lock); if (error) - goto failed; + goto out; goto repeat; } - wait_on_page_locked(swappage); - page_cache_release(swappage); + wait_on_page_locked(page); + page_cache_release(page); goto repeat; } /* We have to do this with page locked to prevent races */ - if (!trylock_page(swappage)) { + if (!trylock_page(page)) { shmem_swp_unmap(entry); spin_unlock(&info->lock); - wait_on_page_locked(swappage); - page_cache_release(swappage); + wait_on_page_locked(page); + page_cache_release(page); goto repeat; } - if (PageWriteback(swappage)) { + if (PageWriteback(page)) { shmem_swp_unmap(entry); spin_unlock(&info->lock); - wait_on_page_writeback(swappage); - unlock_page(swappage); - page_cache_release(swappage); + wait_on_page_writeback(page); + unlock_page(page); + page_cache_release(page); goto repeat; } - if (!PageUptodate(swappage)) { + if (!PageUptodate(page)) { shmem_swp_unmap(entry); spin_unlock(&info->lock); - unlock_page(swappage); - page_cache_release(swappage); + unlock_page(page); + page_cache_release(page); error = -EIO; - goto failed; + goto out; } - if (filepage) { - shmem_swp_set(info, entry, 0); - shmem_swp_unmap(entry); - delete_from_swap_cache(swappage); - spin_unlock(&info->lock); - copy_highpage(filepage, swappage); - unlock_page(swappage); - page_cache_release(swappage); - flush_dcache_page(filepage); - SetPageUptodate(filepage); - set_page_dirty(filepage); - swap_free(swap); - } else if (!(error = add_to_page_cache_locked(swappage, mapping, - idx, GFP_NOWAIT))) { - info->flags |= SHMEM_PAGEIN; - shmem_swp_set(info, entry, 0); - shmem_swp_unmap(entry); - delete_from_swap_cache(swappage); - spin_unlock(&info->lock); - filepage = swappage; - set_page_dirty(filepage); - swap_free(swap); - } else { + error = add_to_page_cache_locked(page, mapping, + idx, GFP_NOWAIT); + if (error) { shmem_swp_unmap(entry); spin_unlock(&info->lock); if (error == -ENOMEM) { @@ -1378,28 +1364,33 @@ repeat: * call memcg's OOM if needed. */ error = mem_cgroup_shmem_charge_fallback( - swappage, - current->mm, - gfp); + page, current->mm, gfp); if (error) { - unlock_page(swappage); - page_cache_release(swappage); - goto failed; + unlock_page(page); + page_cache_release(page); + goto out; } } - unlock_page(swappage); - page_cache_release(swappage); + unlock_page(page); + page_cache_release(page); goto repeat; } - } else if (sgp == SGP_READ && !filepage) { + + info->flags |= SHMEM_PAGEIN; + shmem_swp_set(info, entry, 0); shmem_swp_unmap(entry); - filepage = find_get_page(mapping, idx); - if (filepage && - (!PageUptodate(filepage) || !trylock_page(filepage))) { + delete_from_swap_cache(page); + spin_unlock(&info->lock); + set_page_dirty(page); + swap_free(swap); + + } else if (sgp == SGP_READ) { + shmem_swp_unmap(entry); + page = find_get_page(mapping, idx); + if (page && !trylock_page(page)) { spin_unlock(&info->lock); - wait_on_page_locked(filepage); - page_cache_release(filepage); - filepage = NULL; + wait_on_page_locked(page); + page_cache_release(page); goto repeat; } spin_unlock(&info->lock); @@ -1417,56 +1408,52 @@ repeat: } else if (shmem_acct_block(info->flags)) goto nospace; - if (!filepage) { - int ret; + page = prealloc_page; + prealloc_page = NULL; - filepage = prealloc_page; - prealloc_page = NULL; - - entry = shmem_swp_alloc(info, idx, sgp, gfp); - if (IS_ERR(entry)) - error = PTR_ERR(entry); - else { - swap = *entry; - shmem_swp_unmap(entry); - } - ret = error || swap.val; - if (ret) - mem_cgroup_uncharge_cache_page(filepage); - else - ret = add_to_page_cache_lru(filepage, mapping, + entry = shmem_swp_alloc(info, idx, sgp, gfp); + if (IS_ERR(entry)) + error = PTR_ERR(entry); + else { + swap = *entry; + shmem_swp_unmap(entry); + } + ret = error || swap.val; + if (ret) + mem_cgroup_uncharge_cache_page(page); + else + ret = add_to_page_cache_lru(page, mapping, idx, GFP_NOWAIT); - /* - * At add_to_page_cache_lru() failure, uncharge will - * be done automatically. - */ - if (ret) { - shmem_unacct_blocks(info->flags, 1); - shmem_free_blocks(inode, 1); - spin_unlock(&info->lock); - page_cache_release(filepage); - filepage = NULL; - if (error) - goto failed; - goto repeat; - } - info->flags |= SHMEM_PAGEIN; + /* + * At add_to_page_cache_lru() failure, + * uncharge will be done automatically. + */ + if (ret) { + shmem_unacct_blocks(info->flags, 1); + shmem_free_blocks(inode, 1); + spin_unlock(&info->lock); + page_cache_release(page); + if (error) + goto out; + goto repeat; } + info->flags |= SHMEM_PAGEIN; info->alloced++; spin_unlock(&info->lock); - clear_highpage(filepage); - flush_dcache_page(filepage); - SetPageUptodate(filepage); + clear_highpage(page); + flush_dcache_page(page); + SetPageUptodate(page); if (sgp == SGP_DIRTY) - set_page_dirty(filepage); + set_page_dirty(page); + } else { spin_unlock(&info->lock); error = -ENOMEM; goto out; } done: - *pagep = filepage; + *pagep = page; error = 0; out: if (prealloc_page) { @@ -1482,21 +1469,13 @@ nospace: * but must also avoid reporting a spurious ENOSPC while working on a * full tmpfs. */ - if (!filepage) { - struct page *page = find_get_page(mapping, idx); - if (page) { - spin_unlock(&info->lock); - page_cache_release(page); - goto repeat; - } - } + page = find_get_page(mapping, idx); spin_unlock(&info->lock); - error = -ENOSPC; -failed: - if (filepage) { - unlock_page(filepage); - page_cache_release(filepage); + if (page) { + page_cache_release(page); + goto repeat; } + error = -ENOSPC; goto out; } |