![Amir Goldstein](/assets/img/avatar_default.png)
If fs is frozen after mount and before the first file open, the
update of s_last_mounted bypasses freeze protection and prints out
a WARNING splat:
$ mount /vdf
$ fsfreeze -f /vdf
$ cat /vdf/foo
[ 31.578555] WARNING: CPU: 1 PID: 1415 at
fs/ext4/ext4_jbd2.c:53 ext4_journal_check_start+0x48/0x82
[ 31.614016] Call Trace:
[ 31.614997] __ext4_journal_start_sb+0xe4/0x1a4
[ 31.616771] ? ext4_file_open+0xb6/0x189
[ 31.618094] ext4_file_open+0xb6/0x189
If fs is frozen, skip s_last_mounted update.
[backport hint: to apply to stable tree, need to apply also patches
vfs: add the sb_start_intwrite_trylock() helper
ext4: factor out helper ext4_sample_last_mounted()]
Cc: stable@vger.kernel.org
Fixes: bc0b0d6d69
("ext4: update the s_last_mounted field in the superblock")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
525 lines
13 KiB
C
525 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/fs/ext4/file.c
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*
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* Copyright (C) 1992, 1993, 1994, 1995
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* Remy Card (card@masi.ibp.fr)
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* Laboratoire MASI - Institut Blaise Pascal
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* Universite Pierre et Marie Curie (Paris VI)
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*
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* from
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*
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* linux/fs/minix/file.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* ext4 fs regular file handling primitives
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*
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* 64-bit file support on 64-bit platforms by Jakub Jelinek
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* (jj@sunsite.ms.mff.cuni.cz)
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*/
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#include <linux/time.h>
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#include <linux/fs.h>
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#include <linux/iomap.h>
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#include <linux/mount.h>
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#include <linux/path.h>
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#include <linux/dax.h>
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#include <linux/quotaops.h>
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#include <linux/pagevec.h>
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#include <linux/uio.h>
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#include <linux/mman.h>
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#include "ext4.h"
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#include "ext4_jbd2.h"
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#include "xattr.h"
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#include "acl.h"
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#ifdef CONFIG_FS_DAX
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static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
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{
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struct inode *inode = file_inode(iocb->ki_filp);
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ssize_t ret;
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if (!inode_trylock_shared(inode)) {
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if (iocb->ki_flags & IOCB_NOWAIT)
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return -EAGAIN;
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inode_lock_shared(inode);
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}
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/*
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* Recheck under inode lock - at this point we are sure it cannot
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* change anymore
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*/
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if (!IS_DAX(inode)) {
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inode_unlock_shared(inode);
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/* Fallback to buffered IO in case we cannot support DAX */
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return generic_file_read_iter(iocb, to);
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}
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ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
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inode_unlock_shared(inode);
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file_accessed(iocb->ki_filp);
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return ret;
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}
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#endif
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static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
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{
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if (unlikely(ext4_forced_shutdown(EXT4_SB(file_inode(iocb->ki_filp)->i_sb))))
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return -EIO;
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if (!iov_iter_count(to))
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return 0; /* skip atime */
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#ifdef CONFIG_FS_DAX
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if (IS_DAX(file_inode(iocb->ki_filp)))
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return ext4_dax_read_iter(iocb, to);
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#endif
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return generic_file_read_iter(iocb, to);
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}
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/*
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* Called when an inode is released. Note that this is different
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* from ext4_file_open: open gets called at every open, but release
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* gets called only when /all/ the files are closed.
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*/
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static int ext4_release_file(struct inode *inode, struct file *filp)
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{
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if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
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ext4_alloc_da_blocks(inode);
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ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
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}
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/* if we are the last writer on the inode, drop the block reservation */
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if ((filp->f_mode & FMODE_WRITE) &&
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(atomic_read(&inode->i_writecount) == 1) &&
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!EXT4_I(inode)->i_reserved_data_blocks)
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{
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down_write(&EXT4_I(inode)->i_data_sem);
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ext4_discard_preallocations(inode);
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up_write(&EXT4_I(inode)->i_data_sem);
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}
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if (is_dx(inode) && filp->private_data)
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ext4_htree_free_dir_info(filp->private_data);
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return 0;
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}
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static void ext4_unwritten_wait(struct inode *inode)
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{
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wait_queue_head_t *wq = ext4_ioend_wq(inode);
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wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
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}
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/*
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* This tests whether the IO in question is block-aligned or not.
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* Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
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* are converted to written only after the IO is complete. Until they are
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* mapped, these blocks appear as holes, so dio_zero_block() will assume that
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* it needs to zero out portions of the start and/or end block. If 2 AIO
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* threads are at work on the same unwritten block, they must be synchronized
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* or one thread will zero the other's data, causing corruption.
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*/
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static int
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ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
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{
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struct super_block *sb = inode->i_sb;
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int blockmask = sb->s_blocksize - 1;
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if (pos >= i_size_read(inode))
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return 0;
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if ((pos | iov_iter_alignment(from)) & blockmask)
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return 1;
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return 0;
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}
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/* Is IO overwriting allocated and initialized blocks? */
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static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
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{
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struct ext4_map_blocks map;
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unsigned int blkbits = inode->i_blkbits;
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int err, blklen;
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if (pos + len > i_size_read(inode))
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return false;
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map.m_lblk = pos >> blkbits;
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map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
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blklen = map.m_len;
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err = ext4_map_blocks(NULL, inode, &map, 0);
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/*
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* 'err==len' means that all of the blocks have been preallocated,
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* regardless of whether they have been initialized or not. To exclude
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* unwritten extents, we need to check m_flags.
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*/
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return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
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}
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static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
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{
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struct inode *inode = file_inode(iocb->ki_filp);
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ssize_t ret;
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ret = generic_write_checks(iocb, from);
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if (ret <= 0)
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return ret;
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/*
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* If we have encountered a bitmap-format file, the size limit
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* is smaller than s_maxbytes, which is for extent-mapped files.
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*/
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if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
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struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
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if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
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return -EFBIG;
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iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
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}
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return iov_iter_count(from);
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}
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#ifdef CONFIG_FS_DAX
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static ssize_t
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ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
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{
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struct inode *inode = file_inode(iocb->ki_filp);
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ssize_t ret;
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if (!inode_trylock(inode)) {
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if (iocb->ki_flags & IOCB_NOWAIT)
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return -EAGAIN;
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inode_lock(inode);
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}
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ret = ext4_write_checks(iocb, from);
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if (ret <= 0)
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goto out;
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ret = file_remove_privs(iocb->ki_filp);
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if (ret)
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goto out;
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ret = file_update_time(iocb->ki_filp);
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if (ret)
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goto out;
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ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
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out:
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inode_unlock(inode);
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if (ret > 0)
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ret = generic_write_sync(iocb, ret);
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return ret;
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}
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#endif
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static ssize_t
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ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
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{
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struct inode *inode = file_inode(iocb->ki_filp);
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int o_direct = iocb->ki_flags & IOCB_DIRECT;
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int unaligned_aio = 0;
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int overwrite = 0;
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ssize_t ret;
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if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
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return -EIO;
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#ifdef CONFIG_FS_DAX
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if (IS_DAX(inode))
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return ext4_dax_write_iter(iocb, from);
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#endif
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if (!o_direct && (iocb->ki_flags & IOCB_NOWAIT))
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return -EOPNOTSUPP;
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if (!inode_trylock(inode)) {
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if (iocb->ki_flags & IOCB_NOWAIT)
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return -EAGAIN;
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inode_lock(inode);
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}
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ret = ext4_write_checks(iocb, from);
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if (ret <= 0)
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goto out;
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/*
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* Unaligned direct AIO must be serialized among each other as zeroing
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* of partial blocks of two competing unaligned AIOs can result in data
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* corruption.
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*/
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if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
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!is_sync_kiocb(iocb) &&
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ext4_unaligned_aio(inode, from, iocb->ki_pos)) {
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unaligned_aio = 1;
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ext4_unwritten_wait(inode);
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}
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iocb->private = &overwrite;
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/* Check whether we do a DIO overwrite or not */
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if (o_direct && !unaligned_aio) {
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if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {
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if (ext4_should_dioread_nolock(inode))
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overwrite = 1;
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} else if (iocb->ki_flags & IOCB_NOWAIT) {
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ret = -EAGAIN;
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goto out;
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}
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}
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ret = __generic_file_write_iter(iocb, from);
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inode_unlock(inode);
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if (ret > 0)
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ret = generic_write_sync(iocb, ret);
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return ret;
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out:
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inode_unlock(inode);
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return ret;
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}
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#ifdef CONFIG_FS_DAX
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static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
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enum page_entry_size pe_size)
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{
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int error = 0;
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vm_fault_t result;
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int retries = 0;
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handle_t *handle = NULL;
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struct inode *inode = file_inode(vmf->vma->vm_file);
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struct super_block *sb = inode->i_sb;
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/*
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* We have to distinguish real writes from writes which will result in a
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* COW page; COW writes should *not* poke the journal (the file will not
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* be changed). Doing so would cause unintended failures when mounted
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* read-only.
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*
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* We check for VM_SHARED rather than vmf->cow_page since the latter is
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* unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
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* other sizes, dax_iomap_fault will handle splitting / fallback so that
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* we eventually come back with a COW page.
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*/
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bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
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(vmf->vma->vm_flags & VM_SHARED);
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pfn_t pfn;
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if (write) {
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sb_start_pagefault(sb);
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file_update_time(vmf->vma->vm_file);
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down_read(&EXT4_I(inode)->i_mmap_sem);
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retry:
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handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
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EXT4_DATA_TRANS_BLOCKS(sb));
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if (IS_ERR(handle)) {
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up_read(&EXT4_I(inode)->i_mmap_sem);
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sb_end_pagefault(sb);
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return VM_FAULT_SIGBUS;
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}
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} else {
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down_read(&EXT4_I(inode)->i_mmap_sem);
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}
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result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
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if (write) {
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ext4_journal_stop(handle);
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if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
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ext4_should_retry_alloc(sb, &retries))
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goto retry;
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/* Handling synchronous page fault? */
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if (result & VM_FAULT_NEEDDSYNC)
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result = dax_finish_sync_fault(vmf, pe_size, pfn);
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up_read(&EXT4_I(inode)->i_mmap_sem);
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sb_end_pagefault(sb);
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} else {
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up_read(&EXT4_I(inode)->i_mmap_sem);
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}
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return result;
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}
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static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
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{
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return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
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}
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static const struct vm_operations_struct ext4_dax_vm_ops = {
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.fault = ext4_dax_fault,
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.huge_fault = ext4_dax_huge_fault,
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.page_mkwrite = ext4_dax_fault,
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.pfn_mkwrite = ext4_dax_fault,
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};
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#else
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#define ext4_dax_vm_ops ext4_file_vm_ops
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#endif
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static const struct vm_operations_struct ext4_file_vm_ops = {
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.fault = ext4_filemap_fault,
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.map_pages = filemap_map_pages,
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.page_mkwrite = ext4_page_mkwrite,
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};
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static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
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{
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struct inode *inode = file->f_mapping->host;
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if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
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return -EIO;
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/*
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* We don't support synchronous mappings for non-DAX files. At least
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* until someone comes with a sensible use case.
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*/
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if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC))
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return -EOPNOTSUPP;
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file_accessed(file);
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if (IS_DAX(file_inode(file))) {
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vma->vm_ops = &ext4_dax_vm_ops;
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vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
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} else {
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vma->vm_ops = &ext4_file_vm_ops;
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}
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return 0;
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}
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static int ext4_sample_last_mounted(struct super_block *sb,
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struct vfsmount *mnt)
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{
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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struct path path;
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char buf[64], *cp;
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handle_t *handle;
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int err;
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if (likely(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED))
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return 0;
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if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
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return 0;
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sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
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/*
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* Sample where the filesystem has been mounted and
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* store it in the superblock for sysadmin convenience
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* when trying to sort through large numbers of block
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* devices or filesystem images.
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*/
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memset(buf, 0, sizeof(buf));
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path.mnt = mnt;
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path.dentry = mnt->mnt_root;
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cp = d_path(&path, buf, sizeof(buf));
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err = 0;
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if (IS_ERR(cp))
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goto out;
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handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
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err = PTR_ERR(handle);
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if (IS_ERR(handle))
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goto out;
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BUFFER_TRACE(sbi->s_sbh, "get_write_access");
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err = ext4_journal_get_write_access(handle, sbi->s_sbh);
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if (err)
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goto out_journal;
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strlcpy(sbi->s_es->s_last_mounted, cp,
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sizeof(sbi->s_es->s_last_mounted));
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ext4_handle_dirty_super(handle, sb);
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out_journal:
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ext4_journal_stop(handle);
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out:
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sb_end_intwrite(sb);
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return err;
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}
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static int ext4_file_open(struct inode * inode, struct file * filp)
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{
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int ret;
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if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
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return -EIO;
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ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
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if (ret)
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return ret;
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ret = fscrypt_file_open(inode, filp);
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if (ret)
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return ret;
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/*
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* Set up the jbd2_inode if we are opening the inode for
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* writing and the journal is present
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*/
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if (filp->f_mode & FMODE_WRITE) {
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ret = ext4_inode_attach_jinode(inode);
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if (ret < 0)
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return ret;
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}
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filp->f_mode |= FMODE_NOWAIT;
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return dquot_file_open(inode, filp);
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}
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/*
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* ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
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* by calling generic_file_llseek_size() with the appropriate maxbytes
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* value for each.
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*/
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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) {
|
|
default:
|
|
return generic_file_llseek_size(file, offset, whence,
|
|
maxbytes, i_size_read(inode));
|
|
case SEEK_HOLE:
|
|
inode_lock_shared(inode);
|
|
offset = iomap_seek_hole(inode, offset, &ext4_iomap_ops);
|
|
inode_unlock_shared(inode);
|
|
break;
|
|
case SEEK_DATA:
|
|
inode_lock_shared(inode);
|
|
offset = iomap_seek_data(inode, offset, &ext4_iomap_ops);
|
|
inode_unlock_shared(inode);
|
|
break;
|
|
}
|
|
|
|
if (offset < 0)
|
|
return offset;
|
|
return vfs_setpos(file, offset, maxbytes);
|
|
}
|
|
|
|
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,
|
|
.mmap_supported_flags = MAP_SYNC,
|
|
.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,
|
|
};
|
|
|