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    Subject[PATCH 5.15 543/667] ext4: fix warning in ext4_handle_inode_extension
    Date
    From: Ye Bin <yebin10@huawei.com>

    commit f4534c9fc94d22383f187b9409abb3f9df2e3db3 upstream.

    We got issue as follows:
    EXT4-fs error (device loop0) in ext4_reserve_inode_write:5741: Out of memory
    EXT4-fs error (device loop0): ext4_setattr:5462: inode #13: comm syz-executor.0: mark_inode_dirty error
    EXT4-fs error (device loop0) in ext4_setattr:5519: Out of memory
    EXT4-fs error (device loop0): ext4_ind_map_blocks:595: inode #13: comm syz-executor.0: Can't allocate blocks for non-extent mapped inodes with bigalloc
    ------------[ cut here ]------------
    WARNING: CPU: 1 PID: 4361 at fs/ext4/file.c:301 ext4_file_write_iter+0x11c9/0x1220
    Modules linked in:
    CPU: 1 PID: 4361 Comm: syz-executor.0 Not tainted 5.10.0+ #1
    RIP: 0010:ext4_file_write_iter+0x11c9/0x1220
    RSP: 0018:ffff924d80b27c00 EFLAGS: 00010282
    RAX: ffffffff815a3379 RBX: 0000000000000000 RCX: 000000003b000000
    RDX: ffff924d81601000 RSI: 00000000000009cc RDI: 00000000000009cd
    RBP: 000000000000000d R08: ffffffffbc5a2c6b R09: 0000902e0e52a96f
    R10: ffff902e2b7c1b40 R11: ffff902e2b7c1b40 R12: 000000000000000a
    R13: 0000000000000001 R14: ffff902e0e52aa10 R15: ffffffffffffff8b
    FS: 00007f81a7f65700(0000) GS:ffff902e3bc80000(0000) knlGS:0000000000000000
    CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: ffffffffff600400 CR3: 000000012db88001 CR4: 00000000003706e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
    do_iter_readv_writev+0x2e5/0x360
    do_iter_write+0x112/0x4c0
    do_pwritev+0x1e5/0x390
    __x64_sys_pwritev2+0x7e/0xa0
    do_syscall_64+0x37/0x50
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

    Above issue may happen as follows:
    Assume
    inode.i_size=4096
    EXT4_I(inode)->i_disksize=4096

    step 1: set inode->i_isize = 8192
    ext4_setattr
    if (attr->ia_size != inode->i_size)
    EXT4_I(inode)->i_disksize = attr->ia_size;
    rc = ext4_mark_inode_dirty
    ext4_reserve_inode_write
    ext4_get_inode_loc
    __ext4_get_inode_loc
    sb_getblk --> return -ENOMEM
    ...
    if (!error) ->will not update i_size
    i_size_write(inode, attr->ia_size);
    Now:
    inode.i_size=4096
    EXT4_I(inode)->i_disksize=8192

    step 2: Direct write 4096 bytes
    ext4_file_write_iter
    ext4_dio_write_iter
    iomap_dio_rw ->return error
    if (extend)
    ext4_handle_inode_extension
    WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize);
    ->Then trigger warning.

    To solve above issue, if mark inode dirty failed in ext4_setattr just
    set 'EXT4_I(inode)->i_disksize' with old value.

    Signed-off-by: Ye Bin <yebin10@huawei.com>
    Link: https://lore.kernel.org/r/20220326065351.761952-1-yebin10@huawei.com
    Signed-off-by: Theodore Ts'o <tytso@mit.edu>
    Cc: stable@kernel.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    fs/ext4/inode.c | 4 ++++
    1 file changed, 4 insertions(+)

    --- a/fs/ext4/inode.c
    +++ b/fs/ext4/inode.c
    @@ -5364,6 +5364,7 @@ int ext4_setattr(struct user_namespace *
    if (attr->ia_valid & ATTR_SIZE) {
    handle_t *handle;
    loff_t oldsize = inode->i_size;
    + loff_t old_disksize;
    int shrink = (attr->ia_size < inode->i_size);

    if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
    @@ -5437,6 +5438,7 @@ int ext4_setattr(struct user_namespace *
    inode->i_sb->s_blocksize_bits);

    down_write(&EXT4_I(inode)->i_data_sem);
    + old_disksize = EXT4_I(inode)->i_disksize;
    EXT4_I(inode)->i_disksize = attr->ia_size;
    rc = ext4_mark_inode_dirty(handle, inode);
    if (!error)
    @@ -5448,6 +5450,8 @@ int ext4_setattr(struct user_namespace *
    */
    if (!error)
    i_size_write(inode, attr->ia_size);
    + else
    + EXT4_I(inode)->i_disksize = old_disksize;
    up_write(&EXT4_I(inode)->i_data_sem);
    ext4_journal_stop(handle);
    if (error)

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