diff options
Diffstat (limited to 'mm/filemap.c')
| -rw-r--r-- | mm/filemap.c | 181 |
1 files changed, 149 insertions, 32 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index d1458ecf2f51..920e8dc03251 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -76,8 +76,9 @@ * ->swap_lock (exclusive_swap_page, others) * ->i_pages lock * - * ->i_mutex - * ->i_mmap_rwsem (truncate->unmap_mapping_range) + * ->i_rwsem + * ->invalidate_lock (acquired by fs in truncate path) + * ->i_mmap_rwsem (truncate->unmap_mapping_range) * * ->mmap_lock * ->i_mmap_rwsem @@ -85,9 +86,10 @@ * ->i_pages lock (arch-dependent flush_dcache_mmap_lock) * * ->mmap_lock - * ->lock_page (access_process_vm) + * ->invalidate_lock (filemap_fault) + * ->lock_page (filemap_fault, access_process_vm) * - * ->i_mutex (generic_perform_write) + * ->i_rwsem (generic_perform_write) * ->mmap_lock (fault_in_pages_readable->do_page_fault) * * bdi->wb.list_lock @@ -378,6 +380,32 @@ static int filemap_check_and_keep_errors(struct address_space *mapping) } /** + * filemap_fdatawrite_wbc - start writeback on mapping dirty pages in range + * @mapping: address space structure to write + * @wbc: the writeback_control controlling the writeout + * + * Call writepages on the mapping using the provided wbc to control the + * writeout. + * + * Return: %0 on success, negative error code otherwise. + */ +int filemap_fdatawrite_wbc(struct address_space *mapping, + struct writeback_control *wbc) +{ + int ret; + + if (!mapping_can_writeback(mapping) || + !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) + return 0; + + wbc_attach_fdatawrite_inode(wbc, mapping->host); + ret = do_writepages(mapping, wbc); + wbc_detach_inode(wbc); + return ret; +} +EXPORT_SYMBOL(filemap_fdatawrite_wbc); + +/** * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range * @mapping: address space structure to write * @start: offset in bytes where the range starts @@ -397,7 +425,6 @@ static int filemap_check_and_keep_errors(struct address_space *mapping) int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, loff_t end, int sync_mode) { - int ret; struct writeback_control wbc = { .sync_mode = sync_mode, .nr_to_write = LONG_MAX, @@ -405,14 +432,7 @@ int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, .range_end = end, }; - if (!mapping_can_writeback(mapping) || - !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) - return 0; - - wbc_attach_fdatawrite_inode(&wbc, mapping->host); - ret = do_writepages(mapping, &wbc); - wbc_detach_inode(&wbc); - return ret; + return filemap_fdatawrite_wbc(mapping, &wbc); } static inline int __filemap_fdatawrite(struct address_space *mapping, @@ -1008,6 +1028,44 @@ EXPORT_SYMBOL(__page_cache_alloc); #endif /* + * filemap_invalidate_lock_two - lock invalidate_lock for two mappings + * + * Lock exclusively invalidate_lock of any passed mapping that is not NULL. + * + * @mapping1: the first mapping to lock + * @mapping2: the second mapping to lock + */ +void filemap_invalidate_lock_two(struct address_space *mapping1, + struct address_space *mapping2) +{ + if (mapping1 > mapping2) + swap(mapping1, mapping2); + if (mapping1) + down_write(&mapping1->invalidate_lock); + if (mapping2 && mapping1 != mapping2) + down_write_nested(&mapping2->invalidate_lock, 1); +} +EXPORT_SYMBOL(filemap_invalidate_lock_two); + +/* + * filemap_invalidate_unlock_two - unlock invalidate_lock for two mappings + * + * Unlock exclusive invalidate_lock of any passed mapping that is not NULL. + * + * @mapping1: the first mapping to unlock + * @mapping2: the second mapping to unlock + */ +void filemap_invalidate_unlock_two(struct address_space *mapping1, + struct address_space *mapping2) +{ + if (mapping1) + up_write(&mapping1->invalidate_lock); + if (mapping2 && mapping1 != mapping2) + up_write(&mapping2->invalidate_lock); +} +EXPORT_SYMBOL(filemap_invalidate_unlock_two); + +/* * In order to wait for pages to become available there must be * waitqueues associated with pages. By using a hash table of * waitqueues where the bucket discipline is to maintain all @@ -2368,20 +2426,30 @@ static int filemap_update_page(struct kiocb *iocb, { int error; + if (iocb->ki_flags & IOCB_NOWAIT) { + if (!filemap_invalidate_trylock_shared(mapping)) + return -EAGAIN; + } else { + filemap_invalidate_lock_shared(mapping); + } + if (!trylock_page(page)) { + error = -EAGAIN; if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO)) - return -EAGAIN; + goto unlock_mapping; if (!(iocb->ki_flags & IOCB_WAITQ)) { + filemap_invalidate_unlock_shared(mapping); put_and_wait_on_page_locked(page, TASK_KILLABLE); return AOP_TRUNCATED_PAGE; } error = __lock_page_async(page, iocb->ki_waitq); if (error) - return error; + goto unlock_mapping; } + error = AOP_TRUNCATED_PAGE; if (!page->mapping) - goto truncated; + goto unlock; error = 0; if (filemap_range_uptodate(mapping, iocb->ki_pos, iter, page)) @@ -2392,15 +2460,13 @@ static int filemap_update_page(struct kiocb *iocb, goto unlock; error = filemap_read_page(iocb->ki_filp, mapping, page); - if (error == AOP_TRUNCATED_PAGE) - put_page(page); - return error; -truncated: - unlock_page(page); - put_page(page); - return AOP_TRUNCATED_PAGE; + goto unlock_mapping; unlock: unlock_page(page); +unlock_mapping: + filemap_invalidate_unlock_shared(mapping); + if (error == AOP_TRUNCATED_PAGE) + put_page(page); return error; } @@ -2415,6 +2481,19 @@ static int filemap_create_page(struct file *file, if (!page) return -ENOMEM; + /* + * Protect against truncate / hole punch. Grabbing invalidate_lock here + * assures we cannot instantiate and bring uptodate new pagecache pages + * after evicting page cache during truncate and before actually + * freeing blocks. Note that we could release invalidate_lock after + * inserting the page into page cache as the locked page would then be + * enough to synchronize with hole punching. But there are code paths + * such as filemap_update_page() filling in partially uptodate pages or + * ->readpages() that need to hold invalidate_lock while mapping blocks + * for IO so let's hold the lock here as well to keep locking rules + * simple. + */ + filemap_invalidate_lock_shared(mapping); error = add_to_page_cache_lru(page, mapping, index, mapping_gfp_constraint(mapping, GFP_KERNEL)); if (error == -EEXIST) @@ -2426,9 +2505,11 @@ static int filemap_create_page(struct file *file, if (error) goto error; + filemap_invalidate_unlock_shared(mapping); pagevec_add(pvec, page); return 0; error: + filemap_invalidate_unlock_shared(mapping); put_page(page); return error; } @@ -2967,6 +3048,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) pgoff_t max_off; struct page *page; vm_fault_t ret = 0; + bool mapping_locked = false; max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); if (unlikely(offset >= max_off)) @@ -2976,25 +3058,39 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) * Do we have something in the page cache already? */ page = find_get_page(mapping, offset); - if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) { + if (likely(page)) { /* - * We found the page, so try async readahead before - * waiting for the lock. + * We found the page, so try async readahead before waiting for + * the lock. */ - fpin = do_async_mmap_readahead(vmf, page); - } else if (!page) { + if (!(vmf->flags & FAULT_FLAG_TRIED)) + fpin = do_async_mmap_readahead(vmf, page); + if (unlikely(!PageUptodate(page))) { + filemap_invalidate_lock_shared(mapping); + mapping_locked = true; + } + } else { /* No page in the page cache at all */ count_vm_event(PGMAJFAULT); count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT); ret = VM_FAULT_MAJOR; fpin = do_sync_mmap_readahead(vmf); retry_find: + /* + * See comment in filemap_create_page() why we need + * invalidate_lock + */ + if (!mapping_locked) { + filemap_invalidate_lock_shared(mapping); + mapping_locked = true; + } page = pagecache_get_page(mapping, offset, FGP_CREAT|FGP_FOR_MMAP, vmf->gfp_mask); if (!page) { if (fpin) goto out_retry; + filemap_invalidate_unlock_shared(mapping); return VM_FAULT_OOM; } } @@ -3014,8 +3110,20 @@ retry_find: * We have a locked page in the page cache, now we need to check * that it's up-to-date. If not, it is going to be due to an error. */ - if (unlikely(!PageUptodate(page))) + if (unlikely(!PageUptodate(page))) { + /* + * The page was in cache and uptodate and now it is not. + * Strange but possible since we didn't hold the page lock all + * the time. Let's drop everything get the invalidate lock and + * try again. + */ + if (!mapping_locked) { + unlock_page(page); + put_page(page); + goto retry_find; + } goto page_not_uptodate; + } /* * We've made it this far and we had to drop our mmap_lock, now is the @@ -3026,6 +3134,8 @@ retry_find: unlock_page(page); goto out_retry; } + if (mapping_locked) + filemap_invalidate_unlock_shared(mapping); /* * Found the page and have a reference on it. @@ -3056,6 +3166,7 @@ page_not_uptodate: if (!error || error == AOP_TRUNCATED_PAGE) goto retry_find; + filemap_invalidate_unlock_shared(mapping); return VM_FAULT_SIGBUS; @@ -3067,6 +3178,8 @@ out_retry: */ if (page) put_page(page); + if (mapping_locked) + filemap_invalidate_unlock_shared(mapping); if (fpin) fput(fpin); return ret | VM_FAULT_RETRY; @@ -3437,6 +3550,8 @@ out: * * If the page does not get brought uptodate, return -EIO. * + * The function expects mapping->invalidate_lock to be already held. + * * Return: up to date page on success, ERR_PTR() on failure. */ struct page *read_cache_page(struct address_space *mapping, @@ -3460,6 +3575,8 @@ EXPORT_SYMBOL(read_cache_page); * * If the page does not get brought uptodate, return -EIO. * + * The function expects mapping->invalidate_lock to be already held. + * * Return: up to date page on success, ERR_PTR() on failure. */ struct page *read_cache_page_gfp(struct address_space *mapping, @@ -3704,12 +3821,12 @@ EXPORT_SYMBOL(generic_perform_write); * modification times and calls proper subroutines depending on whether we * do direct IO or a standard buffered write. * - * It expects i_mutex to be grabbed unless we work on a block device or similar + * It expects i_rwsem to be grabbed unless we work on a block device or similar * object which does not need locking at all. * * This function does *not* take care of syncing data in case of O_SYNC write. * A caller has to handle it. This is mainly due to the fact that we want to - * avoid syncing under i_mutex. + * avoid syncing under i_rwsem. * * Return: * * number of bytes written, even for truncated writes @@ -3797,7 +3914,7 @@ EXPORT_SYMBOL(__generic_file_write_iter); * * This is a wrapper around __generic_file_write_iter() to be used by most * filesystems. It takes care of syncing the file in case of O_SYNC file - * and acquires i_mutex as needed. + * and acquires i_rwsem as needed. * Return: * * negative error code if no data has been written at all of * vfs_fsync_range() failed for a synchronous write |