diff options
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/btrfs_inode.h | 1 | ||||
| -rw-r--r-- | fs/btrfs/file.c | 166 | ||||
| -rw-r--r-- | fs/btrfs/inode.c | 167 |
3 files changed, 166 insertions, 168 deletions
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index 100020ca4658..ed8bd15aa3e2 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -496,7 +496,6 @@ void btrfs_merge_delalloc_extent(struct btrfs_inode *inode, struct extent_state void btrfs_split_delalloc_extent(struct btrfs_inode *inode, struct extent_state *orig, u64 split); void btrfs_set_range_writeback(struct btrfs_inode *inode, u64 start, u64 end); -vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf); void btrfs_evict_inode(struct inode *inode); struct inode *btrfs_alloc_inode(struct super_block *sb); void btrfs_destroy_inode(struct inode *inode); diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 0c23053951be..1b972bd05af1 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -2029,6 +2029,172 @@ out_release_extents: goto out; } +/* + * btrfs_page_mkwrite() is not allowed to change the file size as it gets + * called from a page fault handler when a page is first dirtied. Hence we must + * be careful to check for EOF conditions here. We set the page up correctly + * for a written page which means we get ENOSPC checking when writing into + * holes and correct delalloc and unwritten extent mapping on filesystems that + * support these features. + * + * We are not allowed to take the i_mutex here so we have to play games to + * protect against truncate races as the page could now be beyond EOF. Because + * truncate_setsize() writes the inode size before removing pages, once we have + * the page lock we can determine safely if the page is beyond EOF. If it is not + * beyond EOF, then the page is guaranteed safe against truncation until we + * unlock the page. + */ +static vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) +{ + struct page *page = vmf->page; + struct folio *folio = page_folio(page); + struct inode *inode = file_inode(vmf->vma->vm_file); + struct btrfs_fs_info *fs_info = inode_to_fs_info(inode); + struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; + struct btrfs_ordered_extent *ordered; + struct extent_state *cached_state = NULL; + struct extent_changeset *data_reserved = NULL; + unsigned long zero_start; + loff_t size; + vm_fault_t ret; + int ret2; + int reserved = 0; + u64 reserved_space; + u64 page_start; + u64 page_end; + u64 end; + + ASSERT(folio_order(folio) == 0); + + reserved_space = PAGE_SIZE; + + sb_start_pagefault(inode->i_sb); + page_start = page_offset(page); + page_end = page_start + PAGE_SIZE - 1; + end = page_end; + + /* + * Reserving delalloc space after obtaining the page lock can lead to + * deadlock. For example, if a dirty page is locked by this function + * and the call to btrfs_delalloc_reserve_space() ends up triggering + * dirty page write out, then the btrfs_writepages() function could + * end up waiting indefinitely to get a lock on the page currently + * being processed by btrfs_page_mkwrite() function. + */ + ret2 = btrfs_delalloc_reserve_space(BTRFS_I(inode), &data_reserved, + page_start, reserved_space); + if (!ret2) { + ret2 = file_update_time(vmf->vma->vm_file); + reserved = 1; + } + if (ret2) { + ret = vmf_error(ret2); + if (reserved) + goto out; + goto out_noreserve; + } + + /* Make the VM retry the fault. */ + ret = VM_FAULT_NOPAGE; +again: + down_read(&BTRFS_I(inode)->i_mmap_lock); + lock_page(page); + size = i_size_read(inode); + + if ((page->mapping != inode->i_mapping) || + (page_start >= size)) { + /* Page got truncated out from underneath us. */ + goto out_unlock; + } + wait_on_page_writeback(page); + + lock_extent(io_tree, page_start, page_end, &cached_state); + ret2 = set_page_extent_mapped(page); + if (ret2 < 0) { + ret = vmf_error(ret2); + unlock_extent(io_tree, page_start, page_end, &cached_state); + goto out_unlock; + } + + /* + * We can't set the delalloc bits if there are pending ordered + * extents. Drop our locks and wait for them to finish. + */ + ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start, PAGE_SIZE); + if (ordered) { + unlock_extent(io_tree, page_start, page_end, &cached_state); + unlock_page(page); + up_read(&BTRFS_I(inode)->i_mmap_lock); + btrfs_start_ordered_extent(ordered); + btrfs_put_ordered_extent(ordered); + goto again; + } + + if (page->index == ((size - 1) >> PAGE_SHIFT)) { + reserved_space = round_up(size - page_start, fs_info->sectorsize); + if (reserved_space < PAGE_SIZE) { + end = page_start + reserved_space - 1; + btrfs_delalloc_release_space(BTRFS_I(inode), + data_reserved, page_start, + PAGE_SIZE - reserved_space, true); + } + } + + /* + * page_mkwrite gets called when the page is firstly dirtied after it's + * faulted in, but write(2) could also dirty a page and set delalloc + * bits, thus in this case for space account reason, we still need to + * clear any delalloc bits within this page range since we have to + * reserve data&meta space before lock_page() (see above comments). + */ + clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, end, + EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | + EXTENT_DEFRAG, &cached_state); + + ret2 = btrfs_set_extent_delalloc(BTRFS_I(inode), page_start, end, 0, + &cached_state); + if (ret2) { + unlock_extent(io_tree, page_start, page_end, &cached_state); + ret = VM_FAULT_SIGBUS; + goto out_unlock; + } + + /* Page is wholly or partially inside EOF. */ + if (page_start + PAGE_SIZE > size) + zero_start = offset_in_page(size); + else + zero_start = PAGE_SIZE; + + if (zero_start != PAGE_SIZE) + memzero_page(page, zero_start, PAGE_SIZE - zero_start); + + btrfs_folio_clear_checked(fs_info, folio, page_start, PAGE_SIZE); + btrfs_folio_set_dirty(fs_info, folio, page_start, end + 1 - page_start); + btrfs_folio_set_uptodate(fs_info, folio, page_start, end + 1 - page_start); + + btrfs_set_inode_last_sub_trans(BTRFS_I(inode)); + + unlock_extent(io_tree, page_start, page_end, &cached_state); + up_read(&BTRFS_I(inode)->i_mmap_lock); + + btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE); + sb_end_pagefault(inode->i_sb); + extent_changeset_free(data_reserved); + return VM_FAULT_LOCKED; + +out_unlock: + unlock_page(page); + up_read(&BTRFS_I(inode)->i_mmap_lock); +out: + btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE); + btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved, page_start, + reserved_space, (ret != 0)); +out_noreserve: + sb_end_pagefault(inode->i_sb); + extent_changeset_free(data_reserved); + return ret; +} + static const struct vm_operations_struct btrfs_file_vm_ops = { .fault = filemap_fault, .map_pages = filemap_map_pages, diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 1e19cb34b59a..7c009bbc1a5c 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8163,173 +8163,6 @@ next: clear_page_extent_mapped(&folio->page); } -/* - * btrfs_page_mkwrite() is not allowed to change the file size as it gets - * called from a page fault handler when a page is first dirtied. Hence we must - * be careful to check for EOF conditions here. We set the page up correctly - * for a written page which means we get ENOSPC checking when writing into - * holes and correct delalloc and unwritten extent mapping on filesystems that - * support these features. - * - * We are not allowed to take the i_mutex here so we have to play games to - * protect against truncate races as the page could now be beyond EOF. Because - * truncate_setsize() writes the inode size before removing pages, once we have - * the page lock we can determine safely if the page is beyond EOF. If it is not - * beyond EOF, then the page is guaranteed safe against truncation until we - * unlock the page. - */ -vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) -{ - struct page *page = vmf->page; - struct folio *folio = page_folio(page); - struct inode *inode = file_inode(vmf->vma->vm_file); - struct btrfs_fs_info *fs_info = inode_to_fs_info(inode); - struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; - struct btrfs_ordered_extent *ordered; - struct extent_state *cached_state = NULL; - struct extent_changeset *data_reserved = NULL; - unsigned long zero_start; - loff_t size; - vm_fault_t ret; - int ret2; - int reserved = 0; - u64 reserved_space; - u64 page_start; - u64 page_end; - u64 end; - - ASSERT(folio_order(folio) == 0); - - reserved_space = PAGE_SIZE; - - sb_start_pagefault(inode->i_sb); - page_start = page_offset(page); - page_end = page_start + PAGE_SIZE - 1; - end = page_end; - - /* - * Reserving delalloc space after obtaining the page lock can lead to - * deadlock. For example, if a dirty page is locked by this function - * and the call to btrfs_delalloc_reserve_space() ends up triggering - * dirty page write out, then the btrfs_writepages() function could - * end up waiting indefinitely to get a lock on the page currently - * being processed by btrfs_page_mkwrite() function. - */ - ret2 = btrfs_delalloc_reserve_space(BTRFS_I(inode), &data_reserved, - page_start, reserved_space); - if (!ret2) { - ret2 = file_update_time(vmf->vma->vm_file); - reserved = 1; - } - if (ret2) { - ret = vmf_error(ret2); - if (reserved) - goto out; - goto out_noreserve; - } - - ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ -again: - down_read(&BTRFS_I(inode)->i_mmap_lock); - lock_page(page); - size = i_size_read(inode); - - if ((page->mapping != inode->i_mapping) || - (page_start >= size)) { - /* page got truncated out from underneath us */ - goto out_unlock; - } - wait_on_page_writeback(page); - - lock_extent(io_tree, page_start, page_end, &cached_state); - ret2 = set_page_extent_mapped(page); - if (ret2 < 0) { - ret = vmf_error(ret2); - unlock_extent(io_tree, page_start, page_end, &cached_state); - goto out_unlock; - } - - /* - * we can't set the delalloc bits if there are pending ordered - * extents. Drop our locks and wait for them to finish - */ - ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start, - PAGE_SIZE); - if (ordered) { - unlock_extent(io_tree, page_start, page_end, &cached_state); - unlock_page(page); - up_read(&BTRFS_I(inode)->i_mmap_lock); - btrfs_start_ordered_extent(ordered); - btrfs_put_ordered_extent(ordered); - goto again; - } - - if (page->index == ((size - 1) >> PAGE_SHIFT)) { - reserved_space = round_up(size - page_start, - fs_info->sectorsize); - if (reserved_space < PAGE_SIZE) { - end = page_start + reserved_space - 1; - btrfs_delalloc_release_space(BTRFS_I(inode), - data_reserved, page_start, - PAGE_SIZE - reserved_space, true); - } - } - - /* - * page_mkwrite gets called when the page is firstly dirtied after it's - * faulted in, but write(2) could also dirty a page and set delalloc - * bits, thus in this case for space account reason, we still need to - * clear any delalloc bits within this page range since we have to - * reserve data&meta space before lock_page() (see above comments). - */ - clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, end, - EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | - EXTENT_DEFRAG, &cached_state); - - ret2 = btrfs_set_extent_delalloc(BTRFS_I(inode), page_start, end, 0, - &cached_state); - if (ret2) { - unlock_extent(io_tree, page_start, page_end, &cached_state); - ret = VM_FAULT_SIGBUS; - goto out_unlock; - } - - /* page is wholly or partially inside EOF */ - if (page_start + PAGE_SIZE > size) - zero_start = offset_in_page(size); - else - zero_start = PAGE_SIZE; - - if (zero_start != PAGE_SIZE) - memzero_page(page, zero_start, PAGE_SIZE - zero_start); - - btrfs_folio_clear_checked(fs_info, folio, page_start, PAGE_SIZE); - btrfs_folio_set_dirty(fs_info, folio, page_start, end + 1 - page_start); - btrfs_folio_set_uptodate(fs_info, folio, page_start, end + 1 - page_start); - - btrfs_set_inode_last_sub_trans(BTRFS_I(inode)); - - unlock_extent(io_tree, page_start, page_end, &cached_state); - up_read(&BTRFS_I(inode)->i_mmap_lock); - - btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE); - sb_end_pagefault(inode->i_sb); - extent_changeset_free(data_reserved); - return VM_FAULT_LOCKED; - -out_unlock: - unlock_page(page); - up_read(&BTRFS_I(inode)->i_mmap_lock); -out: - btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE); - btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved, page_start, - reserved_space, (ret != 0)); -out_noreserve: - sb_end_pagefault(inode->i_sb); - extent_changeset_free(data_reserved); - return ret; -} - static int btrfs_truncate(struct btrfs_inode *inode, bool skip_writeback) { struct btrfs_truncate_control control = { |