// SPDX-License-Identifier: GPL-2.0-only /* * This file is part of UBIFS. * * Copyright (C) 2006-2008 Nokia Corporation. * * Authors: Artem Bityutskiy (Битюцкий Артём) * Adrian Hunter */ /* * This file implements VFS file and inode operations for regular files, device * nodes and symlinks as well as address space operations. * * UBIFS uses 2 page flags: @PG_private and @PG_checked. @PG_private is set if * the page is dirty and is used for optimization purposes - dirty pages are * not budgeted so the flag shows that 'ubifs_write_end()' should not release * the budget for this page. The @PG_checked flag is set if full budgeting is * required for the page e.g., when it corresponds to a file hole or it is * beyond the file size. The budgeting is done in 'ubifs_write_begin()', because * it is OK to fail in this function, and the budget is released in * 'ubifs_write_end()'. So the @PG_private and @PG_checked flags carry * information about how the page was budgeted, to make it possible to release * the budget properly. * * A thing to keep in mind: inode @i_mutex is locked in most VFS operations we * implement. However, this is not true for 'ubifs_writepage()', which may be * called with @i_mutex unlocked. For example, when flusher thread is doing * background write-back, it calls 'ubifs_writepage()' with unlocked @i_mutex. * At "normal" work-paths the @i_mutex is locked in 'ubifs_writepage()', e.g. * in the "sys_write -> alloc_pages -> direct reclaim path". So, in * 'ubifs_writepage()' we are only guaranteed that the page is locked. * * Similarly, @i_mutex is not always locked in 'ubifs_read_folio()', e.g., the * read-ahead path does not lock it ("sys_read -> generic_file_aio_read -> * ondemand_readahead -> read_folio"). In case of readahead, @I_SYNC flag is not * set as well. However, UBIFS disables readahead. */ #include "ubifs.h" #include #include #include static int read_block(struct inode *inode, void *addr, unsigned int block, struct ubifs_data_node *dn) { struct ubifs_info *c = inode->i_sb->s_fs_info; int err, len, out_len; union ubifs_key key; unsigned int dlen; data_key_init(c, &key, inode->i_ino, block); err = ubifs_tnc_lookup(c, &key, dn); if (err) { if (err == -ENOENT) /* Not found, so it must be a hole */ memset(addr, 0, UBIFS_BLOCK_SIZE); return err; } ubifs_assert(c, le64_to_cpu(dn->ch.sqnum) > ubifs_inode(inode)->creat_sqnum); len = le32_to_cpu(dn->size); if (len <= 0 || len > UBIFS_BLOCK_SIZE) goto dump; dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ; if (IS_ENCRYPTED(inode)) { err = ubifs_decrypt(inode, dn, &dlen, block); if (err) goto dump; } out_len = UBIFS_BLOCK_SIZE; err = ubifs_decompress(c, &dn->data, dlen, addr, &out_len, le16_to_cpu(dn->compr_type)); if (err || len != out_len) goto dump; /* * Data length can be less than a full block, even for blocks that are * not the last in the file (e.g., as a result of making a hole and * appending data). Ensure that the remainder is zeroed out. */ if (len < UBIFS_BLOCK_SIZE) memset(addr + len, 0, UBIFS_BLOCK_SIZE - len); return 0; dump: ubifs_err(c, "bad data node (block %u, inode %lu)", block, inode->i_ino); ubifs_dump_node(c, dn, UBIFS_MAX_DATA_NODE_SZ); return -EINVAL; } static int do_readpage(struct page *page) { void *addr; int err = 0, i; unsigned int block, beyond; struct ubifs_data_node *dn; struct inode *inode = page->mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; loff_t i_size = i_size_read(inode); dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx", inode->i_ino, page->index, i_size, page->flags); ubifs_assert(c, !PageChecked(page)); ubifs_assert(c, !PagePrivate(page)); addr = kmap(page); block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT; beyond = (i_size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT; if (block >= beyond) { /* Reading beyond inode */ SetPageChecked(page); memset(addr, 0, PAGE_SIZE); goto out; } dn = kmalloc(UBIFS_MAX_DATA_NODE_SZ, GFP_NOFS); if (!dn) { err = -ENOMEM; goto error; } i = 0; while (1) { int ret; if (block >= beyond) { /* Reading beyond inode */ err = -ENOENT; memset(addr, 0, UBIFS_BLOCK_SIZE); } else { ret = read_block(inode, addr, block, dn); if (ret) { err = ret; if (err != -ENOENT) break; } else if (block + 1 == beyond) { int dlen = le32_to_cpu(dn->size); int ilen = i_size & (UBIFS_BLOCK_SIZE - 1); if (ilen && ilen < dlen) memset(addr + ilen, 0, dlen - ilen); } } if (++i >= UBIFS_BLOCKS_PER_PAGE) break; block += 1; addr += UBIFS_BLOCK_SIZE; } if (err) { struct ubifs_info *c = inode->i_sb->s_fs_info; if (err == -ENOENT) { /* Not found, so it must be a hole */ SetPageChecked(page); dbg_gen("hole"); goto out_free; } ubifs_err(c, "cannot read page %lu of inode %lu, error %d", page->index, inode->i_ino, err); goto error; } out_free: kfree(dn); out: SetPageUptodate(page); ClearPageError(page); flush_dcache_page(page); kunmap(page); return 0; error: kfree(dn); ClearPageUptodate(page); SetPageError(page); flush_dcache_page(page); kunmap(page); return err; } /** * release_new_page_budget - release budget of a new page. * @c: UBIFS file-system description object * * This is a helper function which releases budget corresponding to the budget * of one new page of data. */ static void release_new_page_budget(struct ubifs_info *c) { struct ubifs_budget_req req = { .recalculate = 1, .new_page = 1 }; ubifs_release_budget(c, &req); } /** * release_existing_page_budget - release budget of an existing page. * @c: UBIFS file-system description object * * This is a helper function which releases budget corresponding to the budget * of changing one page of data which already exists on the flash media. */ static void release_existing_page_budget(struct ubifs_info *c) { struct ubifs_budget_req req = { .dd_growth = c->bi.page_budget}; ubifs_release_budget(c, &req); } static int write_begin_slow(struct address_space *mapping, loff_t pos, unsigned len, struct page **pagep) { struct inode *inode = mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; pgoff_t index = pos >> PAGE_SHIFT; struct ubifs_budget_req req = { .new_page = 1 }; int err, appending = !!(pos + len > inode->i_size); struct page *page; dbg_gen("ino %lu, pos %llu, len %u, i_size %lld", inode->i_ino, pos, len, inode->i_size); /* * At the slow path we have to budget before locking the page, because * budgeting may force write-back, which would wait on locked pages and * deadlock if we had the page locked. At this point we do not know * anything about the page, so assume that this is a new page which is * written to a hole. This corresponds to largest budget. Later the * budget will be amended if this is not true. */ if (appending) /* We are appending data, budget for inode change */ req.dirtied_ino = 1; err = ubifs_budget_space(c, &req); if (unlikely(err)) return err; page = grab_cache_page_write_begin(mapping, index); if (unlikely(!page)) { ubifs_release_budget(c, &req); return -ENOMEM; } if (!PageUptodate(page)) { if (!(pos & ~PAGE_MASK) && len == PAGE_SIZE) SetPageChecked(page); else { err = do_readpage(page); if (err) { unlock_page(page); put_page(page); ubifs_release_budget(c, &req); return err; } } } if (PagePrivate(page)) /* * The page is dirty, which means it was budgeted twice: * o first time the budget was allocated by the task which * made the page dirty and set the PG_private flag; * o and then we budgeted for it for the second time at the * very beginning of this function. * * So what we have to do is to release the page budget we * allocated. */ release_new_page_budget(c); else if (!PageChecked(page)) /* * We are changing a page which already exists on the media. * This means that changing the page does not make the amount * of indexing information larger, and this part of the budget * which we have already acquired may be released. */ ubifs_convert_page_budget(c); if (appending) { struct ubifs_inode *ui = ubifs_inode(inode); /* * 'ubifs_write_end()' is optimized from the fast-path part of * 'ubifs_write_begin()' and expects the @ui_mutex to be locked * if data is appended. */ mutex_lock(&ui->ui_mutex); if (ui->dirty) /* * The inode is dirty already, so we may free the * budget we allocated. */ ubifs_release_dirty_inode_budget(c, ui); } *pagep = page; return 0; } /** * allocate_budget - allocate budget for 'ubifs_write_begin()'. * @c: UBIFS file-system description object * @page: page to allocate budget for * @ui: UBIFS inode object the page belongs to * @appending: non-zero if the page is appended * * This is a helper function for 'ubifs_write_begin()' which allocates budget * for the operation. The budget is allocated differently depending on whether * this is appending, whether the page is dirty or not, and so on. This * function leaves the @ui->ui_mutex locked in case of appending. * * Returns: %0 in case of success and %-ENOSPC in case of failure. */ static int allocate_budget(struct ubifs_info *c, struct page *page, struct ubifs_inode *ui, int appending) { struct ubifs_budget_req req = { .fast = 1 }; if (PagePrivate(page)) { if (!appending) /* * The page is dirty and we are not appending, which * means no budget is needed at all. */ return 0; mutex_lock(&ui->ui_mutex); if (ui->dirty) /* * The page is dirty and we are appending, so the inode * has to be marked as dirty. However, it is already * dirty, so we do not need any budget. We may return, * but @ui->ui_mutex hast to be left locked because we * should prevent write-back from flushing the inode * and freeing the budget. The lock will be released in * 'ubifs_write_end()'. */ return 0; /* * The page is dirty, we are appending, the inode is clean, so * we need to budget the inode change. */ req.dirtied_ino = 1; } else { if (PageChecked(page)) /* * The page corresponds to a hole and does not * exist on the media. So changing it makes * make the amount of indexing information * larger, and we have to budget for a new * page. */ req.new_page = 1; else /* * Not a hole, the change will not add any new * indexing information, budget for page * change. */ req.dirtied_page = 1; if (appending) { mutex_lock(&ui->ui_mutex); if (!ui->dirty) /* * The inode is clean but we will have to mark * it as dirty because we are appending. This * needs a budget. */ req.dirtied_ino = 1; } } return ubifs_budget_space(c, &req); } /* * This function is called when a page of data is going to be written. Since * the page of data will not necessarily go to the flash straight away, UBIFS * has to reserve space on the media for it, which is done by means of * budgeting. * * This is the hot-path of the file-system and we are trying to optimize it as * much as possible. For this reasons it is split on 2 parts - slow and fast. * * There many budgeting cases: * o a new page is appended - we have to budget for a new page and for * changing the inode; however, if the inode is already dirty, there is * no need to budget for it; * o an existing clean page is changed - we have budget for it; if the page * does not exist on the media (a hole), we have to budget for a new * page; otherwise, we may budget for changing an existing page; the * difference between these cases is that changing an existing page does * not introduce anything new to the FS indexing information, so it does * not grow, and smaller budget is acquired in this case; * o an existing dirty page is changed - no need to budget at all, because * the page budget has been acquired by earlier, when the page has been * marked dirty. * * UBIFS budgeting sub-system may force write-back if it thinks there is no * space to reserve. This imposes some locking restrictions and makes it * impossible to take into account the above cases, and makes it impossible to * optimize budgeting. * * The solution for this is that the fast path of 'ubifs_write_begin()' assumes * there is a plenty of flash space and the budget will be acquired quickly, * without forcing write-back. The slow path does not make this assumption. */ static int ubifs_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, struct page **pagep, void **fsdata) { struct inode *inode = mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; struct ubifs_inode *ui = ubifs_inode(inode); pgoff_t index = pos >> PAGE_SHIFT; int err, appending = !!(pos + len > inode->i_size); int skipped_read = 0; struct page *page; ubifs_assert(c, ubifs_inode(inode)->ui_size == inode->i_size); ubifs_assert(c, !c->ro_media && !c->ro_mount); if (unlikely(c->ro_error)) return -EROFS; /* Try out the fast-path part first */ page = grab_cache_page_write_begin(mapping, index); if (unlikely(!page)) return -ENOMEM; if (!PageUptodate(page)) { /* The page is not loaded from the flash */ if (!(pos & ~PAGE_MASK) && len == PAGE_SIZE) { /* * We change whole page so no need to load it. But we * do not know whether this page exists on the media or * not, so we assume the latter because it requires * larger budget. The assumption is that it is better * to budget a bit more than to read the page from the * media. Thus, we are setting the @PG_checked flag * here. */ SetPageChecked(page); skipped_read = 1; } else { err = do_readpage(page); if (err) { unlock_page(page); put_page(page); return err; } } } err = allocate_budget(c, page, ui, appending); if (unlikely(err)) { ubifs_assert(c, err == -ENOSPC); /* * If we skipped reading the page because we were going to * write all of it, then it is not up to date. */ if (skipped_read) ClearPageChecked(page); /* * Budgeting failed which means it would have to force * write-back but didn't, because we set the @fast flag in the * request. Write-back cannot be done now, while we have the * page locked, because it would deadlock. Unlock and free * everything and fall-back to slow-path. */ if (appending) { ubifs_assert(c, mutex_is_locked(&ui->ui_mutex)); mutex_unlock(&ui->ui_mutex); } unlock_page(page); put_page(page); return write_begin_slow(mapping, pos, len, pagep); } /* * Whee, we acquired budgeting quickly - without involving * garbage-collection, committing or forcing write-back. We return * with @ui->ui_mutex locked if we are appending pages, and unlocked * otherwise. This is an optimization (slightly hacky though). */ *pagep = page; return 0; } /** * cancel_budget - cancel budget. * @c: UBIFS file-system description object * @page: page to cancel budget for * @ui: UBIFS inode object the page belongs to * @appending: non-zero if the page is appended * * This is a helper function for a page write operation. It unlocks the * @ui->ui_mutex in case of appending. */ static void cancel_budget(struct ubifs_info *c, struct page *page, struct ubifs_inode *ui, int appending) { if (appending) { if (!ui->dirty) ubifs_release_dirty_inode_budget(c, ui); mutex_unlock(&ui->ui_mutex); } if (!PagePrivate(page)) { if (PageChecked(page)) release_new_page_budget(c); else release_existing_page_budget(c); } } static int ubifs_write_end(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, struct page *page, void *fsdata) { struct inode *inode = mapping->host; struct ubifs_inode *ui = ubifs_inode(inode); struct ubifs_info *c = inode->i_sb->s_fs_info; loff_t end_pos = pos + len; int appending = !!(end_pos > inode->i_size); dbg_gen("ino %lu, pos %llu, pg %lu, len %u, copied %d, i_size %lld", inode->i_ino, pos, page->index, len, copied, inode->i_size); if (unlikely(copied < len && len == PAGE_SIZE)) { /* * VFS copied less data to the page that it intended and * declared in its '->write_begin()' call via the @len * argument. If the page was not up-to-date, and @len was * @PAGE_SIZE, the 'ubifs_write_begin()' function did * not load it from the media (for optimization reasons). This * means that part of the page contains garbage. So read the * page now. */ dbg_gen("copied %d instead of %d, read page and repeat", copied, len); cancel_budget(c, page, ui, appending); ClearPageChecked(page); /* * Return 0 to force VFS to repeat the whole operation, or the * error code if 'do_readpage()' fails. */ copied = do_readpage(page); goto out; } if (len == PAGE_SIZE) SetPageUptodate(page); if (!PagePrivate(page)) { attach_page_private(page, (void *)1); atomic_long_inc(&c->dirty_pg_cnt); __set_page_dirty_nobuffers(page); } if (appending) { i_size_write(inode, end_pos); ui->ui_size = end_pos; /* * Note, we do not set @I_DIRTY_PAGES (which means that the * inode has dirty pages), this has been done in * '__set_page_dirty_nobuffers()'. */ __mark_inode_dirty(inode, I_DIRTY_DATASYNC); ubifs_assert(c, mutex_is_locked(&ui->ui_mutex)); mutex_unlock(&ui->ui_mutex); } out: unlock_page(page); put_page(page); return copied; } /** * populate_page - copy data nodes into a page for bulk-read. * @c: UBIFS file-system description object * @page: page * @bu: bulk-read information * @n: next zbranch slot * * Returns: %0 on success and a negative error code on failure. */ static int populate_page(struct ubifs_info *c, struct page *page, struct bu_info *bu, int *n) { int i = 0, nn = *n, offs = bu->zbranch[0].offs, hole = 0, read = 0; struct inode *inode = page->mapping->host; loff_t i_size = i_size_read(inode); unsigned int page_block; void *addr, *zaddr; pgoff_t end_index; dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx", inode->i_ino, page->index, i_size, page->flags); addr = zaddr = kmap(page); end_index = (i_size - 1) >> PAGE_SHIFT; if (!i_size || page->index > end_index) { hole = 1; memset(addr, 0, PAGE_SIZE); goto out_hole; } page_block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT; while (1) { int err, len, out_len, dlen; if (nn >= bu->cnt) { hole = 1; memset(addr, 0, UBIFS_BLOCK_SIZE); } else if (key_block(c, &bu->zbranch[nn].key) == page_block) { struct ubifs_data_node *dn; dn = bu->buf + (bu->zbranch[nn].offs - offs); ubifs_assert(c, le64_to_cpu(dn->ch.sqnum) > ubifs_inode(inode)->creat_sqnum); len = le32_to_cpu(dn->size); if (len <= 0 || len > UBIFS_BLOCK_SIZE) goto out_err; dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ; out_len = UBIFS_BLOCK_SIZE; if (IS_ENCRYPTED(inode)) { err = ubifs_decrypt(inode, dn, &dlen, page_block); if (err) goto out_err; } err = ubifs_decompress(c, &dn->data, dlen, addr, &out_len, le16_to_cpu(dn->compr_type)); if (err || len != out_len) goto out_err; if (len < UBIFS_BLOCK_SIZE) memset(addr + len, 0, UBIFS_BLOCK_SIZE - len); nn += 1; read = (i << UBIFS_BLOCK_SHIFT) + len; } else if (key_block(c, &bu->zbranch[nn].key) < page_block) { nn += 1; continue; } else { hole = 1; memset(addr, 0, UBIFS_BLOCK_SIZE); } if (++i >= UBIFS_BLOCKS_PER_PAGE) break; addr += UBIFS_BLOCK_SIZE; page_block += 1; } if (end_index == page->index) { int len = i_size & (PAGE_SIZE - 1); if (len && len < read) memset(zaddr + len, 0, read - len); } out_hole: if (hole) { SetPageChecked(page); dbg_gen("hole"); } SetPageUptodate(page); ClearPageError(page); flush_dcache_page(page); kunmap(page); *n = nn; return 0; out_err: ClearPageUptodate(page); SetPageError(page); flush_dcache_page(page); kunmap(page); ubifs_err(c, "bad data node (block %u, inode %lu)", page_block, inode->i_ino); return -EINVAL; } /** * ubifs_do_bulk_read - do bulk-read. * @c: UBIFS file-system description object * @bu: bulk-read information * @page1: first page to read * * Returns: %1 if the bulk-read is done, otherwise %0 is returned. */ static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu, struct page *page1) { pgoff_t offset = page1->index, end_index; struct address_space *mapping = page1->mapping; struct inode *inode = mapping->host; struct ubifs_inode *ui = ubifs_inode(inode); int err, page_idx, page_cnt, ret = 0, n = 0; int allocate = bu->buf ? 0 : 1; loff_t isize; gfp_t ra_gfp_mask = readahead_gfp_mask(mapping) & ~__GFP_FS; err = ubifs_tnc_get_bu_keys(c, bu); if (err) goto out_warn; if (bu->eof) { /* Turn off bulk-read at the end of the file */ ui->read_in_a_row = 1; ui->bulk_read = 0; } page_cnt = bu->blk_cnt >> UBIFS_BLOCKS_PER_PAGE_SHIFT; if (!page_cnt) { /* * This happens when there are multiple blocks per page and the * blocks for the first page we are looking for, are not * together. If all the pages were like this, bulk-read would * reduce performance, so we turn it off for a while. */ goto out_bu_off; } if (bu->cnt) { if (allocate) { /* * Allocate bulk-read buffer depending on how many data * nodes we are going to read. */ bu->buf_len = bu->zbranch[bu->cnt - 1].offs + bu->zbranch[bu->cnt - 1].len - bu->zbranch[0].offs; ubifs_assert(c, bu->buf_len > 0); ubifs_assert(c, bu->buf_len <= c->leb_size); bu->buf = kmalloc(bu->buf_len, GFP_NOFS | __GFP_NOWARN); if (!bu->buf) goto out_bu_off; } err = ubifs_tnc_bulk_read(c, bu); if (err) goto out_warn; } err = populate_page(c, page1, bu, &n); if (err) goto out_warn; unlock_page(page1); ret = 1; isize = i_size_read(inode); if (isize == 0) goto out_free; end_index = ((isize - 1) >> PAGE_SHIFT); for (page_idx = 1; page_idx < page_cnt; page_idx++) { pgoff_t page_offset = offset + page_idx; struct page *page; if (page_offset > end_index) break; page = pagecache_get_page(mapping, page_offset, FGP_LOCK|FGP_ACCESSED|FGP_CREAT|FGP_NOWAIT, ra_gfp_mask); if (!page) break; if (!PageUptodate(page)) err = populate_page(c, page, bu, &n); unlock_page(page); put_page(page); if (err) break; } ui->last_page_read = offset + page_idx - 1; out_free: if (allocate) kfree(bu->buf); return ret; out_warn: ubifs_warn(c, "ignoring error %d and skipping bulk-read", err); goto out_free; out_bu_off: ui->read_in_a_row = ui->bulk_read = 0; goto out_free; } /** * ubifs_bulk_read - determine whether to bulk-read and, if so, do it. * @page: page from which to start bulk-read. * * Some flash media are capable of reading sequentially at faster rates. UBIFS * bulk-read facility is designed to take advantage of that, by reading in one * go consecutive data nodes that are also located consecutively in the same * LEB. * * Returns: %1 if a bulk-read is done and %0 otherwise. */ static int ubifs_bulk_read(struct page *page) { struct inode *inode = page->mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; struct ubifs_inode *ui = ubifs_inode(inode); pgoff_t index = page->index, last_page_read = ui->last_page_read; struct bu_info *bu; int err = 0, allocated = 0; ui->last_page_read = index; if (!c->bulk_read) return 0; /* * Bulk-read is protected by @ui->ui_mutex, but it is an optimization, * so don't bother if we cannot lock the mutex. */ if (!mutex_trylock(&ui->ui_mutex)) return 0; if (index != last_page_read + 1) { /* Turn off bulk-read if we stop reading sequentially */ ui->read_in_a_row = 1; if (ui->bulk_read) ui->bulk_read = 0; goto out_unlock; } if (!ui->bulk_read) { ui->read_in_a_row += 1; if (ui->read_in_a_row < 3) goto out_unlock; /* Three reads in a row, so switch on bulk-read */ ui->bulk_read = 1; } /* * If possible, try to use pre-allocated bulk-read information, which * is protected by @c->bu_mutex. */ if (mutex_trylock(&c->bu_mutex)) bu = &c->bu; else { bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN); if (!bu) goto out_unlock; bu->buf = NULL; allocated = 1; } bu->buf_len = c->max_bu_buf_len; data_key_init(c, &bu->key, inode->i_ino, page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT); err = ubifs_do_bulk_read(c, bu, page); if (!allocated) mutex_unlock(&c->bu_mutex); else kfree(bu); out_unlock: mutex_unlock(&ui->ui_mutex); return err; } static int ubifs_read_folio(struct file *file, struct folio *folio) { struct page *page = &folio->page; if (ubifs_bulk_read(page)) return 0; do_readpage(page); folio_unlock(folio); return 0; } static int do_writepage(struct folio *folio, size_t len) { int err = 0, blen; unsigned int block; void *addr; size_t offset = 0; union ubifs_key key; struct inode *inode = folio->mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; #ifdef UBIFS_DEBUG struct ubifs_inode *ui = ubifs_inode(inode); spin_lock(&ui->ui_lock); ubifs_assert(c, folio->index <= ui->synced_i_size >> PAGE_SHIFT); spin_unlock(&ui->ui_lock); #endif folio_start_writeback(folio); addr = kmap_local_folio(folio, offset); block = folio->index << UBIFS_BLOCKS_PER_PAGE_SHIFT; for (;;) { blen = min_t(size_t, len, UBIFS_BLOCK_SIZE); data_key_init(c, &key, inode->i_ino, block); err = ubifs_jnl_write_data(c, inode, &key, addr, blen); if (err) break; len -= blen; if (!len) break; block += 1; addr += blen; if (folio_test_highmem(folio) && !offset_in_page(addr)) { kunmap_local(addr - blen); offset += PAGE_SIZE; addr = kmap_local_folio(folio, offset); } } kunmap_local(addr); if (err) { mapping_set_error(folio->mapping, err); ubifs_err(c, "cannot write folio %lu of inode %lu, error %d", folio->index, inode->i_ino, err); ubifs_ro_mode(c, err); } ubifs_assert(c, folio->private != NULL); if (folio_test_checked(folio)) release_new_page_budget(c); else release_existing_page_budget(c); atomic_long_dec(&c->dirty_pg_cnt); folio_detach_private(folio); folio_clear_checked(folio); folio_unlock(folio); folio_end_writeback(folio); return err; } /* * When writing-back dirty inodes, VFS first writes-back pages belonging to the * inode, then the inode itself. For UBIFS this may cause a problem. Consider a * situation when a we have an inode with size 0, then a megabyte of data is * appended to the inode, then write-back starts and flushes some amount of the * dirty pages, the journal becomes full, commit happens and finishes, and then * an unclean reboot happens. When the file system is mounted next time, the * inode size would still be 0, but there would be many pages which are beyond * the inode size, they would be indexed and consume flash space. Because the * journal has been committed, the replay would not be able to detect this * situation and correct the inode size. This means UBIFS would have to scan * whole index and correct all inode sizes, which is long an unacceptable. * * To prevent situations like this, UBIFS writes pages back only if they are * within the last synchronized inode size, i.e. the size which has been * written to the flash media last time. Otherwise, UBIFS forces inode * write-back, thus making sure the on-flash inode contains current inode size, * and then keeps writing pages back. * * Some locking issues explanation. 'ubifs_writepage()' first is called with * the page locked, and it locks @ui_mutex. However, write-back does take inode * @i_mutex, which means other VFS operations may be run on this inode at the * same time. And the problematic one is truncation to smaller size, from where * we have to call 'truncate_setsize()', which first changes @inode->i_size, * then drops the truncated pages. And while dropping the pages, it takes the * page lock. This means that 'do_truncation()' cannot call 'truncate_setsize()' * with @ui_mutex locked, because it would deadlock with 'ubifs_writepage()'. * This means that @inode->i_size is changed while @ui_mutex is unlocked. * * XXX(truncate): with the new truncate sequence this is not true anymore, * and the calls to truncate_setsize can be move around freely. They should * be moved to the very end of the truncate sequence. * * But in 'ubifs_writepage()' we have to guarantee that we do not write beyond * inode size. How do we do this if @inode->i_size may became smaller while we * are in the middle of 'ubifs_writepage()'? The UBIFS solution is the * @ui->ui_isize "shadow" field which UBIFS uses instead of @inode->i_size * internally and updates it under @ui_mutex. * * Q: why we do not worry that if we race with truncation, we may end up with a * situation when the inode is truncated while we are in the middle of * 'do_writepage()', so we do write beyond inode size? * A: If we are in the middle of 'do_writepage()', truncation would be locked * on the page lock and it would not write the truncated inode node to the * journal before we have finished. */ static int ubifs_writepage(struct folio *folio, struct writeback_control *wbc, void *data) { struct inode *inode = folio->mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; struct ubifs_inode *ui = ubifs_inode(inode); loff_t i_size = i_size_read(inode), synced_i_size; int err, len = folio_size(folio); dbg_gen("ino %lu, pg %lu, pg flags %#lx", inode->i_ino, folio->index, folio->flags); ubifs_assert(c, folio->private != NULL); /* Is the folio fully outside @i_size? (truncate in progress) */ if (folio_pos(folio) >= i_size) { err = 0; goto out_unlock; } spin_lock(&ui->ui_lock); synced_i_size = ui->synced_i_size; spin_unlock(&ui->ui_lock); /* Is the folio fully inside i_size? */ if (folio_pos(folio) + len <= i_size) { if (folio_pos(folio) >= synced_i_size) { err = inode->i_sb->s_op->write_inode(inode, NULL); if (err) goto out_redirty; /* * The inode has been written, but the write-buffer has * not been synchronized, so in case of an unclean * reboot we may end up with some pages beyond inode * size, but they would be in the journal (because * commit flushes write buffers) and recovery would deal * with this. */ } return do_writepage(folio, len); } /* * The folio straddles @i_size. It must be zeroed out on each and every * writepage invocation because it may be mmapped. "A file is mapped * in multiples of the page size. For a file that is not a multiple of * the page size, the remaining memory is zeroed when mapped, and * writes to that region are not written out to the file." */ len = i_size - folio_pos(folio); folio_zero_segment(folio, len, folio_size(folio)); if (i_size > synced_i_size) { err = inode->i_sb->s_op->write_inode(inode, NULL); if (err) goto out_redirty; } return do_writepage(folio, len); out_redirty: /* * folio_redirty_for_writepage() won't call ubifs_dirty_inode() because * it passes I_DIRTY_PAGES flag while calling __mark_inode_dirty(), so * there is no need to do space budget for dirty inode. */ folio_redirty_for_writepage(wbc, folio); out_unlock: folio_unlock(folio); return err; } static int ubifs_writepages(struct address_space *mapping, struct writeback_control *wbc) { return write_cache_pages(mapping, wbc, ubifs_writepage, NULL); } /** * do_attr_changes - change inode attributes. * @inode: inode to change attributes for * @attr: describes attributes to change */ static void do_attr_changes(struct inode *inode, const struct iattr *attr) { if (attr->ia_valid & ATTR_UID) inode->i_uid = attr->ia_uid; if (attr->ia_valid & ATTR_GID) inode->i_gid = attr->ia_gid; if (attr->ia_valid & ATTR_ATIME) inode_set_atime_to_ts(inode, attr->ia_atime); if (attr->ia_valid & ATTR_MTIME) inode_set_mtime_to_ts(inode, attr->ia_mtime); if (attr->ia_valid & ATTR_CTIME) inode_set_ctime_to_ts(inode, attr->ia_ctime); if (attr->ia_valid & ATTR_MODE) { umode_t mode = attr->ia_mode; if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) mode &= ~S_ISGID; inode->i_mode = mode; } } /** * do_truncation - truncate an inode. * @c: UBIFS file-system description object * @inode: inode to truncate * @attr: inode attribute changes description * * This function implements VFS '->setattr()' call when the inode is truncated * to a smaller size. * * Returns: %0 in case of success and a negative error code * in case of failure. */ static int do_truncation(struct ubifs_info *c, struct inode *inode, const struct iattr *attr) { int err; struct ubifs_budget_req req; loff_t old_size = inode->i_size, new_size = attr->ia_size; int offset = new_size & (UBIFS_BLOCK_SIZE - 1), budgeted = 1; struct ubifs_inode *ui = ubifs_inode(inode); dbg_gen("ino %lu, size %lld -> %lld", inode->i_ino, old_size, new_size); memset(&req, 0, sizeof(struct ubifs_budget_req)); /* * If this is truncation to a smaller size, and we do not truncate on a * block boundary, budget for changing one data block, because the last * block will be re-written. */ if (new_size & (UBIFS_BLOCK_SIZE - 1)) req.dirtied_page = 1; req.dirtied_ino = 1; /* A funny way to budget for truncation node */ req.dirtied_ino_d = UBIFS_TRUN_NODE_SZ; err = ubifs_budget_space(c, &req); if (err) { /* * Treat truncations to zero as deletion and always allow them, * just like we do for '->unlink()'. */ if (new_size || err != -ENOSPC) return err; budgeted = 0; } truncate_setsize(inode, new_size); if (offset) { pgoff_t index = new_size >> PAGE_SHIFT; struct folio *folio; folio = filemap_lock_folio(inode->i_mapping, index); if (!IS_ERR(folio)) { if (folio_test_dirty(folio)) { /* * 'ubifs_jnl_truncate()' will try to truncate * the last data node, but it contains * out-of-date data because the page is dirty. * Write the page now, so that * 'ubifs_jnl_truncate()' will see an already * truncated (and up to date) data node. */ ubifs_assert(c, folio->private != NULL); folio_clear_dirty_for_io(folio); if (UBIFS_BLOCKS_PER_PAGE_SHIFT) offset = offset_in_folio(folio, new_size); err = do_writepage(folio, offset); folio_put(folio); if (err) goto out_budg; /* * We could now tell 'ubifs_jnl_truncate()' not * to read the last block. */ } else { /* * We could 'kmap()' the page and pass the data * to 'ubifs_jnl_truncate()' to save it from * having to read it. */ folio_unlock(folio); folio_put(folio); } } } mutex_lock(&ui->ui_mutex); ui->ui_size = inode->i_size; /* Truncation changes inode [mc]time */ inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode)); /* Other attributes may be changed at the same time as well */ do_attr_changes(inode, attr); err = ubifs_jnl_truncate(c, inode, old_size, new_size); mutex_unlock(&ui->ui_mutex); out_budg: if (budgeted) ubifs_release_budget(c, &req); else { c->bi.nospace = c->bi.nospace_rp = 0; smp_wmb(); } return err; } /** * do_setattr - change inode attributes. * @c: UBIFS file-system description object * @inode: inode to change attributes for * @attr: inode attribute changes description * * This function implements VFS '->setattr()' call for all cases except * truncations to smaller size. * * Returns: %0 in case of success and a negative * error code in case of failure. */ static int do_setattr(struct ubifs_info *c, struct inode *inode, const struct iattr *attr) { int err, release; loff_t new_size = attr->ia_size; struct ubifs_inode *ui = ubifs_inode(inode); struct ubifs_budget_req req = { .dirtied_ino = 1, .dirtied_ino_d = ALIGN(ui->data_len, 8) }; err = ubifs_budget_space(c, &req); if (err) return err; if (attr->ia_valid & ATTR_SIZE) { dbg_gen("size %lld -> %lld", inode->i_size, new_size); truncate_setsize(inode, new_size); } mutex_lock(&ui->ui_mutex); if (attr->ia_valid & ATTR_SIZE) { /* Truncation changes inode [mc]time */ inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode)); /* 'truncate_setsize()' changed @i_size, update @ui_size */ ui->ui_size = inode->i_size; } do_attr_changes(inode, attr); release = ui->dirty; if (attr->ia_valid & ATTR_SIZE) /* * Inode length changed, so we have to make sure * @I_DIRTY_DATASYNC is set. */ __mark_inode_dirty(inode, I_DIRTY_DATASYNC); else mark_inode_dirty_sync(inode); mutex_unlock(&ui->ui_mutex); if (release) ubifs_release_budget(c, &req); if (IS_SYNC(inode)) err = inode->i_sb->s_op->write_inode(inode, NULL); return err; } int ubifs_setattr(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr) { int err; struct inode *inode = d_inode(dentry); struct ubifs_info *c = inode->i_sb->s_fs_info; dbg_gen("ino %lu, mode %#x, ia_valid %#x", inode->i_ino, inode->i_mode, attr->ia_valid); err = setattr_prepare(&nop_mnt_idmap, dentry, attr); if (err) return err; err = dbg_check_synced_i_size(c, inode); if (err) return err; err = fscrypt_prepare_setattr(dentry, attr); if (err) return err; if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size < inode->i_size) /* Truncation to a smaller size */ err = do_truncation(c, inode, attr); else err = do_setattr(c, inode, attr); return err; } static void ubifs_invalidate_folio(struct folio *folio, size_t offset, size_t length) { struct inode *inode = folio->mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; ubifs_assert(c, folio_test_private(folio)); if (offset || length < folio_size(folio)) /* Partial folio remains dirty */ return; if (folio_test_checked(folio)) release_new_page_budget(c); else release_existing_page_budget(c); atomic_long_dec(&c->dirty_pg_cnt); folio_detach_private(folio); folio_clear_checked(folio); } int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync) { struct inode *inode = file->f_mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; int err; dbg_gen("syncing inode %lu", inode->i_ino); if (c->ro_mount) /* * For some really strange reasons VFS does not filter out * 'fsync()' for R/O mounted file-systems as per 2.6.39. */ return 0; err = file_write_and_wait_range(file, start, end); if (err) return err; inode_lock(inode); /* Synchronize the inode unless this is a 'datasync()' call. */ if (!datasync || (inode->i_state & I_DIRTY_DATASYNC)) { err = inode->i_sb->s_op->write_inode(inode, NULL); if (err) goto out; } /* * Nodes related to this inode may still sit in a write-buffer. Flush * them. */ err = ubifs_sync_wbufs_by_inode(c, inode); out: inode_unlock(inode); return err; } /** * mctime_update_needed - check if mtime or ctime update is needed. * @inode: the inode to do the check for * @now: current time * * This helper function checks if the inode mtime/ctime should be updated or * not. If current values of the time-stamps are within the UBIFS inode time * granularity, they are not updated. This is an optimization. * * Returns: %1 if time update is needed, %0 if not */ static inline int mctime_update_needed(const struct inode *inode, const struct timespec64 *now) { struct timespec64 ctime = inode_get_ctime(inode); struct timespec64 mtime = inode_get_mtime(inode); if (!timespec64_equal(&mtime, now) || !timespec64_equal(&ctime, now)) return 1; return 0; } /** * ubifs_update_time - update time of inode. * @inode: inode to update * @flags: time updating control flag determines updating * which time fields of @inode * * This function updates time of the inode. * * Returns: %0 for success or a negative error code otherwise. */ int ubifs_update_time(struct inode *inode, int flags) { struct ubifs_inode *ui = ubifs_inode(inode); struct ubifs_info *c = inode->i_sb->s_fs_info; struct ubifs_budget_req req = { .dirtied_ino = 1, .dirtied_ino_d = ALIGN(ui->data_len, 8) }; int err, release; if (!IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT)) { generic_update_time(inode, flags); return 0; } err = ubifs_budget_space(c, &req); if (err) return err; mutex_lock(&ui->ui_mutex); inode_update_timestamps(inode, flags); release = ui->dirty; __mark_inode_dirty(inode, I_DIRTY_SYNC); mutex_unlock(&ui->ui_mutex); if (release) ubifs_release_budget(c, &req); return 0; } /** * update_mctime - update mtime and ctime of an inode. * @inode: inode to update * * This function updates mtime and ctime of the inode if it is not equivalent to * current time. * * Returns: %0 in case of success and a negative error code in * case of failure. */ static int update_mctime(struct inode *inode) { struct timespec64 now = current_time(inode); struct ubifs_inode *ui = ubifs_inode(inode); struct ubifs_info *c = inode->i_sb->s_fs_info; if (mctime_update_needed(inode, &now)) { int err, release; struct ubifs_budget_req req = { .dirtied_ino = 1, .dirtied_ino_d = ALIGN(ui->data_len, 8) }; err = ubifs_budget_space(c, &req); if (err) return err; mutex_lock(&ui->ui_mutex); inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode)); release = ui->dirty; mark_inode_dirty_sync(inode); mutex_unlock(&ui->ui_mutex); if (release) ubifs_release_budget(c, &req); } return 0; } static ssize_t ubifs_write_iter(struct kiocb *iocb, struct iov_iter *from) { int err = update_mctime(file_inode(iocb->ki_filp)); if (err) return err; return generic_file_write_iter(iocb, from); } static bool ubifs_dirty_folio(struct address_space *mapping, struct folio *folio) { bool ret; struct ubifs_info *c = mapping->host->i_sb->s_fs_info; ret = filemap_dirty_folio(mapping, folio); /* * An attempt to dirty a page without budgeting for it - should not * happen. */ ubifs_assert(c, ret == false); return ret; } static bool ubifs_release_folio(struct folio *folio, gfp_t unused_gfp_flags) { struct inode *inode = folio->mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; if (folio_test_writeback(folio)) return false; /* * Page is private but not dirty, weird? There is one condition * making it happened. ubifs_writepage skipped the page because * page index beyonds isize (for example. truncated by other * process named A), then the page is invalidated by fadvise64 * syscall before being truncated by process A. */ ubifs_assert(c, folio_test_private(folio)); if (folio_test_checked(folio)) release_new_page_budget(c); else release_existing_page_budget(c); atomic_long_dec(&c->dirty_pg_cnt); folio_detach_private(folio); folio_clear_checked(folio); return true; } /* * mmap()d file has taken write protection fault and is being made writable. * UBIFS must ensure page is budgeted for. */ static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf) { struct page *page = vmf->page; struct inode *inode = file_inode(vmf->vma->vm_file); struct ubifs_info *c = inode->i_sb->s_fs_info; struct timespec64 now = current_time(inode); struct ubifs_budget_req req = { .new_page = 1 }; int err, update_time; dbg_gen("ino %lu, pg %lu, i_size %lld", inode->i_ino, page->index, i_size_read(inode)); ubifs_assert(c, !c->ro_media && !c->ro_mount); if (unlikely(c->ro_error)) return VM_FAULT_SIGBUS; /* -EROFS */ /* * We have not locked @page so far so we may budget for changing the * page. Note, we cannot do this after we locked the page, because * budgeting may cause write-back which would cause deadlock. * * At the moment we do not know whether the page is dirty or not, so we * assume that it is not and budget for a new page. We could look at * the @PG_private flag and figure this out, but we may race with write * back and the page state may change by the time we lock it, so this * would need additional care. We do not bother with this at the * moment, although it might be good idea to do. Instead, we allocate * budget for a new page and amend it later on if the page was in fact * dirty. * * The budgeting-related logic of this function is similar to what we * do in 'ubifs_write_begin()' and 'ubifs_write_end()'. Glance there * for more comments. */ update_time = mctime_update_needed(inode, &now); if (update_time) /* * We have to change inode time stamp which requires extra * budgeting. */ req.dirtied_ino = 1; err = ubifs_budget_space(c, &req); if (unlikely(err)) { if (err == -ENOSPC) ubifs_warn(c, "out of space for mmapped file (inode number %lu)", inode->i_ino); return VM_FAULT_SIGBUS; } lock_page(page); if (unlikely(page->mapping != inode->i_mapping || page_offset(page) > i_size_read(inode))) { /* Page got truncated out from underneath us */ goto sigbus; } if (PagePrivate(page)) release_new_page_budget(c); else { if (!PageChecked(page)) ubifs_convert_page_budget(c); attach_page_private(page, (void *)1); atomic_long_inc(&c->dirty_pg_cnt); __set_page_dirty_nobuffers(page); } if (update_time) { int release; struct ubifs_inode *ui = ubifs_inode(inode); mutex_lock(&ui->ui_mutex); inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode)); release = ui->dirty; mark_inode_dirty_sync(inode); mutex_unlock(&ui->ui_mutex); if (release) ubifs_release_dirty_inode_budget(c, ui); } wait_for_stable_page(page); return VM_FAULT_LOCKED; sigbus: unlock_page(page); ubifs_release_budget(c, &req); return VM_FAULT_SIGBUS; } static const struct vm_operations_struct ubifs_file_vm_ops = { .fault = filemap_fault, .map_pages = filemap_map_pages, .page_mkwrite = ubifs_vm_page_mkwrite, }; static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma) { int err; err = generic_file_mmap(file, vma); if (err) return err; vma->vm_ops = &ubifs_file_vm_ops; if (IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT)) file_accessed(file); return 0; } static const char *ubifs_get_link(struct dentry *dentry, struct inode *inode, struct delayed_call *done) { struct ubifs_inode *ui = ubifs_inode(inode); if (!IS_ENCRYPTED(inode)) return ui->data; if (!dentry) return ERR_PTR(-ECHILD); return fscrypt_get_symlink(inode, ui->data, ui->data_len, done); } static int ubifs_symlink_getattr(struct mnt_idmap *idmap, const struct path *path, struct kstat *stat, u32 request_mask, unsigned int query_flags) { ubifs_getattr(idmap, path, stat, request_mask, query_flags); if (IS_ENCRYPTED(d_inode(path->dentry))) return fscrypt_symlink_getattr(path, stat); return 0; } const struct address_space_operations ubifs_file_address_operations = { .read_folio = ubifs_read_folio, .writepages = ubifs_writepages, .write_begin = ubifs_write_begin, .write_end = ubifs_write_end, .invalidate_folio = ubifs_invalidate_folio, .dirty_folio = ubifs_dirty_folio, .migrate_folio = filemap_migrate_folio, .release_folio = ubifs_release_folio, }; const struct inode_operations ubifs_file_inode_operations = { .setattr = ubifs_setattr, .getattr = ubifs_getattr, .listxattr = ubifs_listxattr, .update_time = ubifs_update_time, .fileattr_get = ubifs_fileattr_get, .fileattr_set = ubifs_fileattr_set, }; const struct inode_operations ubifs_symlink_inode_operations = { .get_link = ubifs_get_link, .setattr = ubifs_setattr, .getattr = ubifs_symlink_getattr, .listxattr = ubifs_listxattr, .update_time = ubifs_update_time, }; const struct file_operations ubifs_file_operations = { .llseek = generic_file_llseek, .read_iter = generic_file_read_iter, .write_iter = ubifs_write_iter, .mmap = ubifs_file_mmap, .fsync = ubifs_fsync, .unlocked_ioctl = ubifs_ioctl, .splice_read = filemap_splice_read, .splice_write = iter_file_splice_write, .open = fscrypt_file_open, #ifdef CONFIG_COMPAT .compat_ioctl = ubifs_compat_ioctl, #endif };