/* * linux/fs/ext4/file.c * * Copyright (C) 1992, 1993, 1994, 1995 * Remy Card (card@masi.ibp.fr) * Laboratoire MASI - Institut Blaise Pascal * Universite Pierre et Marie Curie (Paris VI) * * from * * linux/fs/minix/file.c * * Copyright (C) 1991, 1992 Linus Torvalds * * ext4 fs regular file handling primitives * * 64-bit file support on 64-bit platforms by Jakub Jelinek * (jj@sunsite.ms.mff.cuni.cz) */ #include <linux/time.h> #include <linux/fs.h> #include <linux/jbd2.h> #include <linux/mount.h> #include <linux/path.h> #include <linux/aio.h> #include <linux/quotaops.h> #include <linux/pagevec.h> #include "ext4.h" #include "ext4_jbd2.h" #include "xattr.h" #include "acl.h" /* * Called when an inode is released. Note that this is different * from ext4_file_open: open gets called at every open, but release * gets called only when /all/ the files are closed. */ static int ext4_release_file(struct inode *inode, struct file *filp) { if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) { ext4_alloc_da_blocks(inode); ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE); } /* if we are the last writer on the inode, drop the block reservation */ if ((filp->f_mode & FMODE_WRITE) && (atomic_read(&inode->i_writecount) == 1) && !EXT4_I(inode)->i_reserved_data_blocks) { down_write(&EXT4_I(inode)->i_data_sem); ext4_discard_preallocations(inode); up_write(&EXT4_I(inode)->i_data_sem); } if (is_dx(inode) && filp->private_data) ext4_htree_free_dir_info(filp->private_data); return 0; } static void ext4_unwritten_wait(struct inode *inode) { wait_queue_head_t *wq = ext4_ioend_wq(inode); wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0)); } /* * This tests whether the IO in question is block-aligned or not. * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they * are converted to written only after the IO is complete. Until they are * mapped, these blocks appear as holes, so dio_zero_block() will assume that * it needs to zero out portions of the start and/or end block. If 2 AIO * threads are at work on the same unwritten block, they must be synchronized * or one thread will zero the other's data, causing corruption. */ static int ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos) { struct super_block *sb = inode->i_sb; int blockmask = sb->s_blocksize - 1; if (pos >= i_size_read(inode)) return 0; if ((pos | iov_iter_alignment(from)) & blockmask) return 1; return 0; } static ssize_t ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) { struct file *file = iocb->ki_filp; struct inode *inode = file_inode(iocb->ki_filp); struct mutex *aio_mutex = NULL; struct blk_plug plug; int o_direct = file->f_flags & O_DIRECT; int overwrite = 0; size_t length = iov_iter_count(from); ssize_t ret; loff_t pos = iocb->ki_pos; /* * Unaligned direct AIO must be serialized; see comment above * In the case of O_APPEND, assume that we must always serialize */ if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) && !is_sync_kiocb(iocb) && (file->f_flags & O_APPEND || ext4_unaligned_aio(inode, from, pos))) { aio_mutex = ext4_aio_mutex(inode); mutex_lock(aio_mutex); ext4_unwritten_wait(inode); } mutex_lock(&inode->i_mutex); if (file->f_flags & O_APPEND) iocb->ki_pos = pos = i_size_read(inode); /* * If we have encountered a bitmap-format file, the size limit * is smaller than s_maxbytes, which is for extent-mapped files. */ if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) { struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); if ((pos > sbi->s_bitmap_maxbytes) || (pos == sbi->s_bitmap_maxbytes && length > 0)) { mutex_unlock(&inode->i_mutex); ret = -EFBIG; goto errout; } if (pos + length > sbi->s_bitmap_maxbytes) iov_iter_truncate(from, sbi->s_bitmap_maxbytes - pos); } if (o_direct) { blk_start_plug(&plug); iocb->private = &overwrite; /* check whether we do a DIO overwrite or not */ if (ext4_should_dioread_nolock(inode) && !aio_mutex && !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) { struct ext4_map_blocks map; unsigned int blkbits = inode->i_blkbits; int err, len; map.m_lblk = pos >> blkbits; map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits) - map.m_lblk; len = map.m_len; err = ext4_map_blocks(NULL, inode, &map, 0); /* * 'err==len' means that all of blocks has * been preallocated no matter they are * initialized or not. For excluding * unwritten extents, we need to check * m_flags. There are two conditions that * indicate for initialized extents. 1) If we * hit extent cache, EXT4_MAP_MAPPED flag is * returned; 2) If we do a real lookup, * non-flags are returned. So we should check * these two conditions. */ if (err == len && (map.m_flags & EXT4_MAP_MAPPED)) overwrite = 1; } } ret = __generic_file_write_iter(iocb, from); mutex_unlock(&inode->i_mutex); if (ret > 0) { ssize_t err; err = generic_write_sync(file, iocb->ki_pos - ret, ret); if (err < 0) ret = err; } if (o_direct) blk_finish_plug(&plug); errout: if (aio_mutex) mutex_unlock(aio_mutex); return ret; } static const struct vm_operations_struct ext4_file_vm_ops = { .fault = filemap_fault, .map_pages = filemap_map_pages, .page_mkwrite = ext4_page_mkwrite, .remap_pages = generic_file_remap_pages, }; static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) { file_accessed(file); vma->vm_ops = &ext4_file_vm_ops; return 0; } static int ext4_file_open(struct inode * inode, struct file * filp) { struct super_block *sb = inode->i_sb; struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); struct vfsmount *mnt = filp->f_path.mnt; struct path path; char buf[64], *cp; if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) && !(sb->s_flags & MS_RDONLY))) { sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED; /* * Sample where the filesystem has been mounted and * store it in the superblock for sysadmin convenience * when trying to sort through large numbers of block * devices or filesystem images. */ memset(buf, 0, sizeof(buf)); path.mnt = mnt; path.dentry = mnt->mnt_root; cp = d_path(&path, buf, sizeof(buf)); if (!IS_ERR(cp)) { handle_t *handle; int err; handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1); if (IS_ERR(handle)) return PTR_ERR(handle); BUFFER_TRACE(sbi->s_sbh, "get_write_access"); err = ext4_journal_get_write_access(handle, sbi->s_sbh); if (err) { ext4_journal_stop(handle); return err; } strlcpy(sbi->s_es->s_last_mounted, cp, sizeof(sbi->s_es->s_last_mounted)); ext4_handle_dirty_super(handle, sb); ext4_journal_stop(handle); } } /* * Set up the jbd2_inode if we are opening the inode for * writing and the journal is present */ if (filp->f_mode & FMODE_WRITE) { int ret = ext4_inode_attach_jinode(inode); if (ret < 0) return ret; } return dquot_file_open(inode, filp); } /* * Here we use ext4_map_blocks() to get a block mapping for a extent-based * file rather than ext4_ext_walk_space() because we can introduce * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same * function. When extent status tree has been fully implemented, it will * track all extent status for a file and we can directly use it to * retrieve the offset for SEEK_DATA/SEEK_HOLE. */ /* * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to * lookup page cache to check whether or not there has some data between * [startoff, endoff] because, if this range contains an unwritten extent, * we determine this extent as a data or a hole according to whether the * page cache has data or not. */ static int ext4_find_unwritten_pgoff(struct inode *inode, int whence, struct ext4_map_blocks *map, loff_t *offset) { struct pagevec pvec; unsigned int blkbits; pgoff_t index; pgoff_t end; loff_t endoff; loff_t startoff; loff_t lastoff; int found = 0; blkbits = inode->i_sb->s_blocksize_bits; startoff = *offset; lastoff = startoff; endoff = (loff_t)(map->m_lblk + map->m_len) << blkbits; index = startoff >> PAGE_CACHE_SHIFT; end = endoff >> PAGE_CACHE_SHIFT; pagevec_init(&pvec, 0); do { int i, num; unsigned long nr_pages; num = min_t(pgoff_t, end - index, PAGEVEC_SIZE); nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index, (pgoff_t)num); if (nr_pages == 0) { if (whence == SEEK_DATA) break; BUG_ON(whence != SEEK_HOLE); /* * If this is the first time to go into the loop and * offset is not beyond the end offset, it will be a * hole at this offset */ if (lastoff == startoff || lastoff < endoff) found = 1; break; } /* * If this is the first time to go into the loop and * offset is smaller than the first page offset, it will be a * hole at this offset. */ if (lastoff == startoff && whence == SEEK_HOLE && lastoff < page_offset(pvec.pages[0])) { found = 1; break; } for (i = 0; i < nr_pages; i++) { struct page *page = pvec.pages[i]; struct buffer_head *bh, *head; /* * If the current offset is not beyond the end of given * range, it will be a hole. */ if (lastoff < endoff && whence == SEEK_HOLE && page->index > end) { found = 1; *offset = lastoff; goto out; } lock_page(page); if (unlikely(page->mapping != inode->i_mapping)) { unlock_page(page); continue; } if (!page_has_buffers(page)) { unlock_page(page); continue; } if (page_has_buffers(page)) { lastoff = page_offset(page); bh = head = page_buffers(page); do { if (buffer_uptodate(bh) || buffer_unwritten(bh)) { if (whence == SEEK_DATA) found = 1; } else { if (whence == SEEK_HOLE) found = 1; } if (found) { *offset = max_t(loff_t, startoff, lastoff); unlock_page(page); goto out; } lastoff += bh->b_size; bh = bh->b_this_page; } while (bh != head); } lastoff = page_offset(page) + PAGE_SIZE; unlock_page(page); } /* * The no. of pages is less than our desired, that would be a * hole in there. */ if (nr_pages < num && whence == SEEK_HOLE) { found = 1; *offset = lastoff; break; } index = pvec.pages[i - 1]->index + 1; pagevec_release(&pvec); } while (index <= end); out: pagevec_release(&pvec); return found; } /* * ext4_seek_data() retrieves the offset for SEEK_DATA. */ static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize) { struct inode *inode = file->f_mapping->host; struct ext4_map_blocks map; struct extent_status es; ext4_lblk_t start, last, end; loff_t dataoff, isize; int blkbits; int ret = 0; mutex_lock(&inode->i_mutex); isize = i_size_read(inode); if (offset >= isize) { mutex_unlock(&inode->i_mutex); return -ENXIO; } blkbits = inode->i_sb->s_blocksize_bits; start = offset >> blkbits; last = start; end = isize >> blkbits; dataoff = offset; do { map.m_lblk = last; map.m_len = end - last + 1; ret = ext4_map_blocks(NULL, inode, &map, 0); if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) { if (last != start) dataoff = (loff_t)last << blkbits; break; } /* * If there is a delay extent at this offset, * it will be as a data. */ ext4_es_find_delayed_extent_range(inode, last, last, &es); if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) { if (last != start) dataoff = (loff_t)last << blkbits; break; } /* * If there is a unwritten extent at this offset, * it will be as a data or a hole according to page * cache that has data or not. */ if (map.m_flags & EXT4_MAP_UNWRITTEN) { int unwritten; unwritten = ext4_find_unwritten_pgoff(inode, SEEK_DATA, &map, &dataoff); if (unwritten) break; } last++; dataoff = (loff_t)last << blkbits; } while (last <= end); mutex_unlock(&inode->i_mutex); if (dataoff > isize) return -ENXIO; return vfs_setpos(file, dataoff, maxsize); } /* * ext4_seek_hole() retrieves the offset for SEEK_HOLE. */ static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize) { struct inode *inode = file->f_mapping->host; struct ext4_map_blocks map; struct extent_status es; ext4_lblk_t start, last, end; loff_t holeoff, isize; int blkbits; int ret = 0; mutex_lock(&inode->i_mutex); isize = i_size_read(inode); if (offset >= isize) { mutex_unlock(&inode->i_mutex); return -ENXIO; } blkbits = inode->i_sb->s_blocksize_bits; start = offset >> blkbits; last = start; end = isize >> blkbits; holeoff = offset; do { map.m_lblk = last; map.m_len = end - last + 1; ret = ext4_map_blocks(NULL, inode, &map, 0); if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) { last += ret; holeoff = (loff_t)last << blkbits; continue; } /* * If there is a delay extent at this offset, * we will skip this extent. */ ext4_es_find_delayed_extent_range(inode, last, last, &es); if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) { last = es.es_lblk + es.es_len; holeoff = (loff_t)last << blkbits; continue; } /* * If there is a unwritten extent at this offset, * it will be as a data or a hole according to page * cache that has data or not. */ if (map.m_flags & EXT4_MAP_UNWRITTEN) { int unwritten; unwritten = ext4_find_unwritten_pgoff(inode, SEEK_HOLE, &map, &holeoff); if (!unwritten) { last += ret; holeoff = (loff_t)last << blkbits; continue; } } /* find a hole */ break; } while (last <= end); mutex_unlock(&inode->i_mutex); if (holeoff > isize) holeoff = isize; return vfs_setpos(file, holeoff, maxsize); } /* * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values * by calling generic_file_llseek_size() with the appropriate maxbytes * value for each. */ loff_t ext4_llseek(struct file *file, loff_t offset, int whence) { struct inode *inode = file->f_mapping->host; loff_t maxbytes; if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes; else maxbytes = inode->i_sb->s_maxbytes; switch (whence) { case SEEK_SET: case SEEK_CUR: case SEEK_END: return generic_file_llseek_size(file, offset, whence, maxbytes, i_size_read(inode)); case SEEK_DATA: return ext4_seek_data(file, offset, maxbytes); case SEEK_HOLE: return ext4_seek_hole(file, offset, maxbytes); } return -EINVAL; } const struct file_operations ext4_file_operations = { .llseek = ext4_llseek, .read = new_sync_read, .write = new_sync_write, .read_iter = generic_file_read_iter, .write_iter = ext4_file_write_iter, .unlocked_ioctl = ext4_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = ext4_compat_ioctl, #endif .mmap = ext4_file_mmap, .open = ext4_file_open, .release = ext4_release_file, .fsync = ext4_sync_file, .splice_read = generic_file_splice_read, .splice_write = iter_file_splice_write, .fallocate = ext4_fallocate, }; const struct inode_operations ext4_file_inode_operations = { .setattr = ext4_setattr, .getattr = ext4_getattr, .setxattr = generic_setxattr, .getxattr = generic_getxattr, .listxattr = ext4_listxattr, .removexattr = generic_removexattr, .get_acl = ext4_get_acl, .set_acl = ext4_set_acl, .fiemap = ext4_fiemap, };