diff options
| -rw-r--r-- | mm/shmem.c | 88 |
1 files changed, 43 insertions, 45 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 262d7117344..dc17551d060 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -852,7 +852,7 @@ static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) { - struct inode *inode; + struct address_space *mapping; unsigned long idx; unsigned long size; unsigned long limit; @@ -875,8 +875,10 @@ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, s if (size > SHMEM_NR_DIRECT) size = SHMEM_NR_DIRECT; offset = shmem_find_swp(entry, ptr, ptr+size); - if (offset >= 0) + if (offset >= 0) { + shmem_swp_balance_unmap(); goto found; + } if (!info->i_indirect) goto lost2; @@ -914,11 +916,11 @@ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, s if (size > ENTRIES_PER_PAGE) size = ENTRIES_PER_PAGE; offset = shmem_find_swp(entry, ptr, ptr+size); - shmem_swp_unmap(ptr); if (offset >= 0) { shmem_dir_unmap(dir); goto found; } + shmem_swp_unmap(ptr); } } lost1: @@ -928,8 +930,7 @@ lost2: return 0; found: idx += offset; - inode = igrab(&info->vfs_inode); - spin_unlock(&info->lock); + ptr += offset; /* * Move _head_ to start search for next from here. @@ -940,37 +941,18 @@ found: */ if (shmem_swaplist.next != &info->swaplist) list_move_tail(&shmem_swaplist, &info->swaplist); - mutex_unlock(&shmem_swaplist_mutex); - error = 1; - if (!inode) - goto out; /* - * Charge page using GFP_KERNEL while we can wait. - * Charged back to the user(not to caller) when swap account is used. - * add_to_page_cache() will be called with GFP_NOWAIT. + * We rely on shmem_swaplist_mutex, not only to protect the swaplist, + * but also to hold up shmem_evict_inode(): so inode cannot be freed + * beneath us (pagelock doesn't help until the page is in pagecache). */ - error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); - if (error) - goto out; - error = radix_tree_preload(GFP_KERNEL); - if (error) { - mem_cgroup_uncharge_cache_page(page); - goto out; - } - error = 1; - - spin_lock(&info->lock); - ptr = shmem_swp_entry(info, idx, NULL); - if (ptr && ptr->val == entry.val) { - error = add_to_page_cache_locked(page, inode->i_mapping, - idx, GFP_NOWAIT); - /* does mem_cgroup_uncharge_cache_page on error */ - } else /* we must compensate for our precharge above */ - mem_cgroup_uncharge_cache_page(page); + mapping = info->vfs_inode.i_mapping; + error = add_to_page_cache_locked(page, mapping, idx, GFP_NOWAIT); + /* which does mem_cgroup_uncharge_cache_page on error */ if (error == -EEXIST) { - struct page *filepage = find_get_page(inode->i_mapping, idx); + struct page *filepage = find_get_page(mapping, idx); error = 1; if (filepage) { /* @@ -990,14 +972,8 @@ found: swap_free(entry); error = 1; /* not an error, but entry was found */ } - if (ptr) - shmem_swp_unmap(ptr); + shmem_swp_unmap(ptr); spin_unlock(&info->lock); - radix_tree_preload_end(); -out: - unlock_page(page); - page_cache_release(page); - iput(inode); /* allows for NULL */ return error; } @@ -1009,6 +985,26 @@ int shmem_unuse(swp_entry_t entry, struct page *page) struct list_head *p, *next; struct shmem_inode_info *info; int found = 0; + int error; + + /* + * Charge page using GFP_KERNEL while we can wait, before taking + * the shmem_swaplist_mutex which might hold up shmem_writepage(). + * Charged back to the user (not to caller) when swap account is used. + * add_to_page_cache() will be called with GFP_NOWAIT. + */ + error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); + if (error) + goto out; + /* + * Try to preload while we can wait, to not make a habit of + * draining atomic reserves; but don't latch on to this cpu, + * it's okay if sometimes we get rescheduled after this. + */ + error = radix_tree_preload(GFP_KERNEL); + if (error) + goto uncharge; + radix_tree_preload_end(); mutex_lock(&shmem_swaplist_mutex); list_for_each_safe(p, next, &shmem_swaplist) { @@ -1016,17 +1012,19 @@ int shmem_unuse(swp_entry_t entry, struct page *page) found = shmem_unuse_inode(info, entry, page); cond_resched(); if (found) - goto out; + break; } mutex_unlock(&shmem_swaplist_mutex); - /* - * Can some race bring us here? We've been holding page lock, - * so I think not; but would rather try again later than BUG() - */ + +uncharge: + if (!found) + mem_cgroup_uncharge_cache_page(page); + if (found < 0) + error = found; +out: unlock_page(page); page_cache_release(page); -out: - return (found < 0) ? found : 0; + return error; } /* |