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Diffstat (limited to 'fs/ubifs/file.c')
| -rw-r--r-- | fs/ubifs/file.c | 1275 |
1 files changed, 1275 insertions, 0 deletions
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c new file mode 100644 index 00000000000..005a3b854d9 --- /dev/null +++ b/fs/ubifs/file.c @@ -0,0 +1,1275 @@ +/* + * 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> + +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(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; + } + } + 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) +{ + 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(mapping, index); + 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(mapping, index); + 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); + } + + /* + * 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; +} + +static int ubifs_readpage(struct file *file, struct page *page) +{ + 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); + 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) + return err; + + 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: + ubifs_release_budget(c, &req); + 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 = ui->data_len }; + + 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, ia_valid %#x", inode->i_ino, 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 = ui->data_len }; + + 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 + * 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("out of space for mmapped file " + "(inode number %lu)", inode->i_ino); + return err; + } + + lock_page(page); + if (unlikely(page->mapping != inode->i_mapping || + page_offset(page) > i_size_read(inode))) { + /* Page got truncated out from underneath us */ + err = -EINVAL; + goto out_unlock; + } + + if (PagePrivate(page)) + release_new_page_budget(c); + else { + if (!PageChecked(page)) + ubifs_convert_page_budget(c); + SetPagePrivate(page); + 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->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_dirty_inode_budget(c, ui); + } + + unlock_page(page); + return 0; + +out_unlock: + unlock_page(page); + ubifs_release_budget(c, &req); + return err; +} + +static struct vm_operations_struct ubifs_file_vm_ops = { + .fault = filemap_fault, + .page_mkwrite = ubifs_vm_page_mkwrite, +}; + +static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma) +{ + int err; + + /* 'generic_file_mmap()' takes care of NOMMU case */ + err = generic_file_mmap(file, vma); + if (err) + return err; + vma->vm_ops = &ubifs_file_vm_ops; + return 0; +} + +struct address_space_operations ubifs_file_address_operations = { + .readpage = ubifs_readpage, + .writepage = ubifs_writepage, + .write_begin = ubifs_write_begin, + .write_end = ubifs_write_end, + .invalidatepage = ubifs_invalidatepage, + .set_page_dirty = ubifs_set_page_dirty, + .releasepage = ubifs_releasepage, +}; + +struct inode_operations ubifs_file_inode_operations = { + .setattr = ubifs_setattr, + .getattr = ubifs_getattr, +#ifdef CONFIG_UBIFS_FS_XATTR + .setxattr = ubifs_setxattr, + .getxattr = ubifs_getxattr, + .listxattr = ubifs_listxattr, + .removexattr = ubifs_removexattr, +#endif +}; + +struct inode_operations ubifs_symlink_inode_operations = { + .readlink = generic_readlink, + .follow_link = ubifs_follow_link, + .setattr = ubifs_setattr, + .getattr = ubifs_getattr, +}; + +struct file_operations ubifs_file_operations = { + .llseek = generic_file_llseek, + .read = do_sync_read, + .write = do_sync_write, + .aio_read = generic_file_aio_read, + .aio_write = ubifs_aio_write, + .mmap = ubifs_file_mmap, + .fsync = ubifs_fsync, + .unlocked_ioctl = ubifs_ioctl, + .splice_read = generic_file_splice_read, +#ifdef CONFIG_COMPAT + .compat_ioctl = ubifs_compat_ioctl, +#endif +}; |