litmus-rt.git - The LITMUS^RT kernel.

diff options

Diffstat (limited to 'fs/btrfs/ref-cache.h')

-rw-r--r--

1 files changed, 0 insertions, 1 deletions


diff --git a/fs/btrfs/ref-cache.h b/fs/btrfs/ref-cache.h index 16f3183d7c59..bc283ad2db73 100644 --- a/fs/btrfs/ref-cache.h +++ b/fs/btrfs/ref-cache.h
@@ -73,5 +73,4 @@ int btrfs_add_leaf_ref(struct btrfs_root root, struct btrfs_leaf_ref ref,
73	int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen,	73	int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen,
74	int shared);	74	int shared);
75	int btrfs_remove_leaf_ref(struct btrfs_root root, struct btrfs_leaf_ref ref);	75	int btrfs_remove_leaf_ref(struct btrfs_root root, struct btrfs_leaf_ref ref);
76
77	#endif	76	#endif

/* * This file is part of UBIFS. * * Copyright (C) 2006-2008 Nokia Corporation. * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published by * the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for * more details. * * You should have received a copy of the GNU General Public License along with * this program; if not, write to the Free Software Foundation, Inc., 51 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA * * Authors: Artem Bityutskiy (Битюцкий Артём) * Adrian Hunter */ /* * This file implements VFS file and inode operations of 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 budgeting purposes - dirty pages should not be * budgeted. 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 just 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 the information about how the page * was budgeted, to make it possible to release the budget properly. * * A thing to keep in mind: inode's 'i_mutex' is locked in most VFS operations * we implement. However, this is not true for '->writepage()', which might be * called with 'i_mutex' unlocked. For example, when pdflush is performing * write-back, it calls 'writepage()' with unlocked 'i_mutex', although the * inode has 'I_LOCK' flag in this case. At "normal" work-paths 'i_mutex' is * locked in '->writepage', e.g. in "sys_write -> alloc_pages -> direct reclaim * path'. So, in '->writepage()' we are only guaranteed that the page is * locked. * * Similarly, 'i_mutex' does not have to be locked in readpage(), e.g., * readahead path does not have it locked ("sys_read -> generic_file_aio_read * -> ondemand_readahead -> readpage"). In case of readahead, 'I_LOCK' flag is * not set as well. However, UBIFS disables readahead. * * This, for example means that there might be 2 concurrent '->writepage()' * calls for the same inode, but different inode dirty pages. */ #include "ubifs.h" #include <linux/mount.h> #include <linux/namei.h> 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(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; out_len = UBIFS_BLOCK_SIZE; err = ubifs_decompress(&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("bad data node (block %u, inode %lu)", block, inode->i_ino); dbg_dump_node(c, dn); 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; 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(!PageChecked(page)); ubifs_assert(!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_CACHE_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) { if (err == -ENOENT) { /* Not found, so it must be a hole */ SetPageChecked(page); dbg_gen("hole"); goto out_free; } ubifs_err("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 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->page_budget}; ubifs_release_budget(c, &req); } static int write_begin_slow(struct address_space *mapping, loff_t pos, unsigned len, struct page **pagep, unsigned flags) { struct inode *inode = mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; pgoff_t index = pos >> PAGE_CACHE_SHIFT; struct ubifs_budget_req req = { .new_page = 1 }; int uninitialized_var(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, flags); if (unlikely(!page)) { ubifs_release_budget(c, &req); return -ENOMEM; } if (!PageUptodate(page)) { if (!(pos & ~PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE) SetPageChecked(page); else { err = do_readpage(page); if (err) { unlock_page(page); page_cache_release(page); return err; } } SetPageUptodate(page); ClearPageError(page); } 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 zero * 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, unsigned flags, 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_CACHE_SHIFT; int uninitialized_var(err), appending = !!(pos + len > inode->i_size); struct page *page; ubifs_assert(ubifs_inode(inode)->ui_size == inode->i_size); if (unlikely(c->ro_media)) return -EROFS; /* Try out the fast-path part first */ page = grab_cache_page_write_begin(mapping, index, flags); if (unlikely(!page)) return -ENOMEM; if (!PageUptodate(page)) { /* The page is not loaded from the flash */ if (!(pos & ~PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE) /* * We change whole page so no need to load it. But we * have to set the @PG_checked flag to make the further * code the page is new. This might be not true, but it * is better to budget more that to read the page from * the media. */ SetPageChecked(page); else { err = do_readpage(page); if (err) { unlock_page(page); page_cache_release(page); return err; } } SetPageUptodate(page); ClearPageError(page); } err = allocate_budget(c, page, ui, appending); if (unlikely(err)) { ubifs_assert(err == -ENOSPC); /* * 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(mutex_is_locked(&ui->ui_mutex)); mutex_unlock(&ui->ui_mutex); } unlock_page(page); page_cache_release(page); return write_begin_slow(mapping, pos, len, pagep, flags); } /* * Whee, we aquired budgeting quickly - without involving * garbage-collection, committing or forceing 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_CACHE_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_CACHE_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); /* * Return 0 to force VFS to repeat the whole operation, or the * error code if 'do_readpage()' failes. */ copied = do_readpage(page); goto out; } if (!PagePrivate(page)) { SetPagePrivate(page); 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(mutex_is_locked(&ui->ui_mutex)); mutex_unlock(&ui->ui_mutex); } out: unlock_page(page); page_cache_release(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 * * This function 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_CACHE_SHIFT; if (!i_size || page->index > end_index) { hole = 1; memset(addr, 0, PAGE_CACHE_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(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; err = ubifs_decompress(&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_CACHE_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("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 * * This function 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; 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(bu->buf_len > 0); ubifs_assert(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_CACHE_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 = find_or_create_page(mapping, page_offset, GFP_NOFS | __GFP_COLD); if (!page) break; if (!PageUptodate(page)) err = populate_page(c, page, bu, &n); unlock_page(page); page_cache_release(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("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. This function 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_readpage(struct file *file, struct page *page) { if (ubifs_bulk_read(page)) return 0; do_readpage(page); unlock_page(page); return 0; } static int do_writepage(struct page *page, int len) { int err = 0, i, blen; unsigned int block; void *addr; union ubifs_key key; struct inode *inode = page->mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; #ifdef UBIFS_DEBUG spin_lock(&ui->ui_lock); ubifs_assert(page->index <= ui->synced_i_size << PAGE_CACHE_SIZE); spin_unlock(&ui->ui_lock); #endif /* Update radix tree tags */ set_page_writeback(page); addr = kmap(page); block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT; i = 0; while (len) { blen = min_t(int, 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; if (++i >= UBIFS_BLOCKS_PER_PAGE) break; block += 1; addr += blen; len -= blen; } if (err) { SetPageError(page); ubifs_err("cannot write page %lu of inode %lu, error %d", page->index, inode->i_ino, err); ubifs_ro_mode(c, err); } ubifs_assert(PagePrivate(page)); if (PageChecked(page)) release_new_page_budget(c); else release_existing_page_budget(c); atomic_long_dec(&c->dirty_pg_cnt); ClearPagePrivate(page); ClearPageChecked(page); kunmap(page); unlock_page(page); end_page_writeback(page); 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 last synchronized inode size, i.e. the 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 'vmtruncate()', 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 'vmtruncate()' with * @ui_mutex locked, because it would deadlock with 'ubifs_writepage()'. This * means that @inode->i_size is changed while @ui_mutex is unlocked. * * 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 page *page, struct writeback_control *wbc) { struct inode *inode = page->mapping->host; struct ubifs_inode *ui = ubifs_inode(inode); loff_t i_size = i_size_read(inode), synced_i_size; pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; int err, len = i_size & (PAGE_CACHE_SIZE - 1); void *kaddr; dbg_gen("ino %lu, pg %lu, pg flags %#lx", inode->i_ino, page->index, page->flags); ubifs_assert(PagePrivate(page)); /* Is the page fully outside @i_size? (truncate in progress) */ if (page->index > end_index || (page->index == end_index && !len)) { err = 0; goto out_unlock; } spin_lock(&ui->ui_lock); synced_i_size = ui->synced_i_size; spin_unlock(&ui->ui_lock); /* Is the page fully inside @i_size? */ if (page->index < end_index) { if (page->index >= synced_i_size >> PAGE_CACHE_SHIFT) { err = inode->i_sb->s_op->write_inode(inode, 1); if (err) goto out_unlock; /* * 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(page, PAGE_CACHE_SIZE); } /* * The page 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." */ kaddr = kmap_atomic(page, KM_USER0); memset(kaddr + len, 0, PAGE_CACHE_SIZE - len); flush_dcache_page(page); kunmap_atomic(kaddr, KM_USER0); if (i_size > synced_i_size) { err = inode->i_sb->s_op->write_inode(inode, 1); if (err) goto out_unlock; } return do_writepage(page, len); out_unlock: unlock_page(page); return err; } /** * 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->i_atime = timespec_trunc(attr->ia_atime, inode->i_sb->s_time_gran); if (attr->ia_valid & ATTR_MTIME) inode->i_mtime = timespec_trunc(attr->ia_mtime, inode->i_sb->s_time_gran); if (attr->ia_valid & ATTR_CTIME) inode->i_ctime = timespec_trunc(attr->ia_ctime, inode->i_sb->s_time_gran); 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 zero 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; } err = vmtruncate(inode, new_size); if (err) goto out_budg; if (offset) { pgoff_t index = new_size >> PAGE_CACHE_SHIFT; struct page *page; page = find_lock_page(inode->i_mapping, index); if (page) { if (PageDirty(page)) { /* * '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(PagePrivate(page)); clear_page_dirty_for_io(page); if (UBIFS_BLOCKS_PER_PAGE_SHIFT) offset = new_size & (PAGE_CACHE_SIZE - 1); err = do_writepage(page, offset); page_cache_release(page); 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. */ unlock_page(page); page_cache_release(page); } } } mutex_lock(&ui->ui_mutex); ui->ui_size = inode->i_size; /* Truncation changes inode [mc]time */ inode->i_mtime = inode->i_ctime = ubifs_current_time(inode); /* The 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->nospace = c->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 zero 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); err = vmtruncate(inode, new_size); if (err) goto out; } mutex_lock(&ui->ui_mutex); if (attr->ia_valid & ATTR_SIZE) { /* Truncation changes inode [mc]time */ inode->i_mtime = inode->i_ctime = ubifs_current_time(inode); /* 'vmtruncate()' 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_SYNC | 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, 1); return err; out: ubifs_release_budget(c, &req); return err; } int ubifs_setattr(struct dentry *dentry, struct iattr *attr) { int err; struct inode *inode = dentry->d_inode; 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 = inode_change_ok(inode, attr); if (err) return err; err = dbg_check_synced_i_size(inode); 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_invalidatepage(struct page *page, unsigned long offset) { struct inode *inode = page->mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; ubifs_assert(PagePrivate(page)); if (offset) /* Partial page remains dirty */ return; if (PageChecked(page)) release_new_page_budget(c); else release_existing_page_budget(c); atomic_long_dec(&c->dirty_pg_cnt); ClearPagePrivate(page); ClearPageChecked(page); } static void *ubifs_follow_link(struct dentry *dentry, struct nameidata *nd) { struct ubifs_inode *ui = ubifs_inode(dentry->d_inode); nd_set_link(nd, ui->data); return NULL; } int ubifs_fsync(struct file *file, struct dentry *dentry, int datasync) { struct inode *inode = dentry->d_inode; struct ubifs_info *c = inode->i_sb->s_fs_info; int err; dbg_gen("syncing inode %lu", inode->i_ino); /* * VFS has already synchronized dirty pages for this 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, 1); if (err) return err; } /* * Nodes related to this inode may still sit in a write-buffer. Flush * them. */ err = ubifs_sync_wbufs_by_inode(c, inode); if (err) return err; return 0; } /** * 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. */ static inline int mctime_update_needed(const struct inode *inode, const struct timespec *now) { if (!timespec_equal(&inode->i_mtime, now) || !timespec_equal(&inode->i_ctime, now)) return 1; return 0; } /** * update_ctime - update mtime and ctime of an inode. * @c: UBIFS file-system description object * @inode: inode to update * * This function updates mtime and ctime of the inode if it is not equivalent to * current time. Returns zero in case of success and a negative error code in * case of failure. */ static int update_mctime(struct ubifs_info *c, struct inode *inode) { struct timespec now = ubifs_current_time(inode); struct ubifs_inode *ui = ubifs_inode(inode); 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->i_mtime = inode->i_ctime = ubifs_current_time(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_aio_write(struct kiocb *iocb, const struct iovec *iov, unsigned long nr_segs, loff_t pos) { int err; ssize_t ret; struct inode *inode = iocb->ki_filp->f_mapping->host; struct ubifs_info *c = inode->i_sb->s_fs_info; err = update_mctime(c, inode); if (err) return err; ret = generic_file_aio_write(iocb, iov, nr_segs, pos); if (ret < 0) return ret; if (ret > 0 && (IS_SYNC(inode) || iocb->ki_filp->f_flags & O_SYNC)) { err = ubifs_sync_wbufs_by_inode(c, inode); if (err) return err; } return ret; } static int ubifs_set_page_dirty(struct page *page) { int ret; ret = __set_page_dirty_nobuffers(page); /* * An attempt to dirty a page without budgeting for it - should not * happen. */ ubifs_assert(ret == 0); return ret; } static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags) { /* * An attempt to release a dirty page without budgeting for it - should * not happen. */ if (PageWriteback(page)) return 0; ubifs_assert(PagePrivate(page)); ubifs_assert(0); ClearPagePrivate(page); ClearPageChecked(page); return 1; } /* * mmap()d file has taken write protection fault and is being made * writable. UBIFS must ensure page is budgeted for. */ static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page) { struct inode *inode = vma->vm_file->f_path.dentry->d_inode; struct ubifs_info *c = inode->i_sb->s_fs_info; struct timespec now = ubifs_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(!(inode->i_sb->s_flags & MS_RDONLY)); if (unlikely(c->ro_media)) return -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


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