// SPDX-License-Identifier: GPL-2.0 /* * 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 #include #include #include #include #include #include #include #include "ext4.h" #include "ext4_jbd2.h" #include "xattr.h" #include "acl.h" #ifdef CONFIG_FS_DAX static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) { struct inode *inode = file_inode(iocb->ki_filp); ssize_t ret; if (iocb->ki_flags & IOCB_NOWAIT) { if (!inode_trylock_shared(inode)) return -EAGAIN; } else { inode_lock_shared(inode); } /* * Recheck under inode lock - at this point we are sure it cannot * change anymore */ if (!IS_DAX(inode)) { inode_unlock_shared(inode); /* Fallback to buffered IO in case we cannot support DAX */ return generic_file_read_iter(iocb, to); } ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops); inode_unlock_shared(inode); file_accessed(iocb->ki_filp); return ret; } #endif static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to) { if (unlikely(ext4_forced_shutdown(EXT4_SB(file_inode(iocb->ki_filp)->i_sb)))) return -EIO; if (!iov_iter_count(to)) return 0; /* skip atime */ #ifdef CONFIG_FS_DAX if (IS_DAX(file_inode(iocb->ki_filp))) return ext4_dax_read_iter(iocb, to); #endif return generic_file_read_iter(iocb, to); } /* * 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 >= ALIGN(i_size_read(inode), sb->s_blocksize)) return 0; if ((pos | iov_iter_alignment(from)) & blockmask) return 1; return 0; } /* Is IO overwriting allocated and initialized blocks? */ static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len) { struct ext4_map_blocks map; unsigned int blkbits = inode->i_blkbits; int err, blklen; if (pos + len > i_size_read(inode)) return false; map.m_lblk = pos >> blkbits; map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits); blklen = map.m_len; err = ext4_map_blocks(NULL, inode, &map, 0); /* * 'err==len' means that all of the blocks have been preallocated, * regardless of whether they have been initialized or not. To exclude * unwritten extents, we need to check m_flags. */ return err == blklen && (map.m_flags & EXT4_MAP_MAPPED); } static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from) { struct inode *inode = file_inode(iocb->ki_filp); ssize_t ret; ret = generic_write_checks(iocb, from); if (ret <= 0) return ret; if (unlikely(IS_IMMUTABLE(inode))) return -EPERM; /* * 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 (iocb->ki_pos >= sbi->s_bitmap_maxbytes) return -EFBIG; iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos); } return iov_iter_count(from); } #ifdef CONFIG_FS_DAX static ssize_t ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) { struct inode *inode = file_inode(iocb->ki_filp); ssize_t ret; if (iocb->ki_flags & IOCB_NOWAIT) { if (!inode_trylock(inode)) return -EAGAIN; } else { inode_lock(inode); } ret = ext4_write_checks(iocb, from); if (ret <= 0) goto out; ret = file_remove_privs(iocb->ki_filp); if (ret) goto out; ret = file_update_time(iocb->ki_filp); if (ret) goto out; ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops); out: inode_unlock(inode); if (ret > 0) ret = generic_write_sync(iocb, ret); return ret; } #endif static ssize_t ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) { struct inode *inode = file_inode(iocb->ki_filp); int o_direct = iocb->ki_flags & IOCB_DIRECT; int unaligned_aio = 0; int overwrite = 0; ssize_t ret; if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) return -EIO; #ifdef CONFIG_FS_DAX if (IS_DAX(inode)) return ext4_dax_write_iter(iocb, from); #endif if (!o_direct && (iocb->ki_flags & IOCB_NOWAIT)) return -EOPNOTSUPP; if (!inode_trylock(inode)) { if (iocb->ki_flags & IOCB_NOWAIT) return -EAGAIN; inode_lock(inode); } ret = ext4_write_checks(iocb, from); if (ret <= 0) goto out; /* * Unaligned direct AIO must be serialized among each other as zeroing * of partial blocks of two competing unaligned AIOs can result in data * corruption. */ if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) && !is_sync_kiocb(iocb) && ext4_unaligned_aio(inode, from, iocb->ki_pos)) { unaligned_aio = 1; ext4_unwritten_wait(inode); } iocb->private = &overwrite; /* Check whether we do a DIO overwrite or not */ if (o_direct && !unaligned_aio) { if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) { if (ext4_should_dioread_nolock(inode)) overwrite = 1; } else if (iocb->ki_flags & IOCB_NOWAIT) { ret = -EAGAIN; goto out; } } ret = __generic_file_write_iter(iocb, from); /* * Unaligned direct AIO must be the only IO in flight. Otherwise * overlapping aligned IO after unaligned might result in data * corruption. */ if (ret == -EIOCBQUEUED && unaligned_aio) ext4_unwritten_wait(inode); inode_unlock(inode); if (ret > 0) ret = generic_write_sync(iocb, ret); return ret; out: inode_unlock(inode); return ret; } #ifdef CONFIG_FS_DAX static int ext4_dax_huge_fault(struct vm_fault *vmf, enum page_entry_size pe_size) { int result; handle_t *handle = NULL; struct inode *inode = file_inode(vmf->vma->vm_file); struct super_block *sb = inode->i_sb; /* * We have to distinguish real writes from writes which will result in a * COW page; COW writes should *not* poke the journal (the file will not * be changed). Doing so would cause unintended failures when mounted * read-only. * * We check for VM_SHARED rather than vmf->cow_page since the latter is * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for * other sizes, dax_iomap_fault will handle splitting / fallback so that * we eventually come back with a COW page. */ bool write = (vmf->flags & FAULT_FLAG_WRITE) && (vmf->vma->vm_flags & VM_SHARED); if (write) { sb_start_pagefault(sb); file_update_time(vmf->vma->vm_file); down_read(&EXT4_I(inode)->i_mmap_sem); handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE, EXT4_DATA_TRANS_BLOCKS(sb)); } else { down_read(&EXT4_I(inode)->i_mmap_sem); } if (!IS_ERR(handle)) result = dax_iomap_fault(vmf, pe_size, &ext4_iomap_ops); else result = VM_FAULT_SIGBUS; if (write) { if (!IS_ERR(handle)) ext4_journal_stop(handle); up_read(&EXT4_I(inode)->i_mmap_sem); sb_end_pagefault(sb); } else { up_read(&EXT4_I(inode)->i_mmap_sem); } return result; } static int ext4_dax_fault(struct vm_fault *vmf) { return ext4_dax_huge_fault(vmf, PE_SIZE_PTE); } static const struct vm_operations_struct ext4_dax_vm_ops = { .fault = ext4_dax_fault, .huge_fault = ext4_dax_huge_fault, .page_mkwrite = ext4_dax_fault, .pfn_mkwrite = ext4_dax_fault, }; #else #define ext4_dax_vm_ops ext4_file_vm_ops #endif static const struct vm_operations_struct ext4_file_vm_ops = { .fault = ext4_filemap_fault, .map_pages = filemap_map_pages, .page_mkwrite = ext4_page_mkwrite, }; static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) { struct inode *inode = file->f_mapping->host; if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) return -EIO; file_accessed(file); if (IS_DAX(file_inode(file))) { vma->vm_ops = &ext4_dax_vm_ops; vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE; } else { 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 dentry *dir; struct path path; char buf[64], *cp; int ret; if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) return -EIO; if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) && !sb_rdonly(sb))) { 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); } } if (ext4_encrypted_inode(inode)) { ret = fscrypt_get_encryption_info(inode); if (ret) return -EACCES; if (!fscrypt_has_encryption_key(inode)) return -ENOKEY; } dir = dget_parent(file_dentry(filp)); if (ext4_encrypted_inode(d_inode(dir)) && !fscrypt_has_permitted_context(d_inode(dir), inode)) { ext4_warning(inode->i_sb, "Inconsistent encryption contexts: %lu/%lu", (unsigned long) d_inode(dir)->i_ino, (unsigned long) inode->i_ino); dput(dir); return -EPERM; } dput(dir); /* * Set up the jbd2_inode if we are opening the inode for * writing and the journal is present */ if (filp->f_mode & FMODE_WRITE) { ret = ext4_inode_attach_jinode(inode); if (ret < 0) return ret; } filp->f_mode |= FMODE_NOWAIT; 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, ext4_lblk_t end_blk, 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)end_blk << blkbits; index = startoff >> PAGE_SHIFT; end = (endoff - 1) >> PAGE_SHIFT; pagevec_init(&pvec, 0); do { int i; unsigned long nr_pages; nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index, end); if (nr_pages == 0) break; for (i = 0; i < nr_pages; i++) { struct page *page = pvec.pages[i]; struct buffer_head *bh, *head; /* * If current offset is smaller than the page offset, * there is a hole at this offset. */ if (whence == SEEK_HOLE && lastoff < endoff && lastoff < page_offset(pvec.pages[i])) { 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 (lastoff + bh->b_size <= startoff) goto next; 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; } next: lastoff += bh->b_size; bh = bh->b_this_page; } while (bh != head); } lastoff = page_offset(page) + PAGE_SIZE; unlock_page(page); } pagevec_release(&pvec); } while (index <= end); /* There are no pages upto endoff - that would be a hole in there. */ if (whence == SEEK_HOLE && lastoff < endoff) { found = 1; *offset = lastoff; } 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 extent_status es; ext4_lblk_t start, last, end; loff_t dataoff, isize; int blkbits; int ret; inode_lock(inode); isize = i_size_read(inode); if (offset < 0 || offset >= isize) { inode_unlock(inode); return -ENXIO; } blkbits = inode->i_sb->s_blocksize_bits; start = offset >> blkbits; last = start; end = isize >> blkbits; dataoff = offset; do { ret = ext4_get_next_extent(inode, last, end - last + 1, &es); if (ret <= 0) { /* No extent found -> no data */ if (ret == 0) ret = -ENXIO; inode_unlock(inode); return ret; } last = es.es_lblk; if (last != start) dataoff = (loff_t)last << blkbits; if (!ext4_es_is_unwritten(&es)) 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 (ext4_find_unwritten_pgoff(inode, SEEK_DATA, es.es_lblk + es.es_len, &dataoff)) break; last += es.es_len; dataoff = (loff_t)last << blkbits; cond_resched(); } while (last <= end); inode_unlock(inode); 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 extent_status es; ext4_lblk_t start, last, end; loff_t holeoff, isize; int blkbits; int ret; inode_lock(inode); isize = i_size_read(inode); if (offset < 0 || offset >= isize) { inode_unlock(inode); return -ENXIO; } blkbits = inode->i_sb->s_blocksize_bits; start = offset >> blkbits; last = start; end = isize >> blkbits; holeoff = offset; do { ret = ext4_get_next_extent(inode, last, end - last + 1, &es); if (ret < 0) { inode_unlock(inode); return ret; } /* Found a hole? */ if (ret == 0 || es.es_lblk > last) { if (last != start) holeoff = (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 (ext4_es_is_unwritten(&es) && ext4_find_unwritten_pgoff(inode, SEEK_HOLE, last + es.es_len, &holeoff)) break; last += es.es_len; holeoff = (loff_t)last << blkbits; cond_resched(); } while (last <= end); inode_unlock(inode); 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_iter = ext4_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, .get_unmapped_area = thp_get_unmapped_area, .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_file_getattr, .listxattr = ext4_listxattr, .get_acl = ext4_get_acl, .set_acl = ext4_set_acl, .fiemap = ext4_fiemap, };