On 22/06/15 09:58PM, Ye Bin wrote:
> We got issue as follows:
> ------------[ cut here ]------------
> WARNING: CPU: 3 PID: 9310 at fs/ext4/inode.c:3441 ext4_iomap_begin+0x182/0x5d0
> RIP: 0010:ext4_iomap_begin+0x182/0x5d0
> RSP: 0018:ffff88812460fa08 EFLAGS: 00010293
> RAX: ffff88811f168000 RBX: 0000000000000000 RCX: ffffffff97793c12
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
> RBP: ffff88812c669160 R08: ffff88811f168000 R09: ffffed10258cd20f
> R10: ffff88812c669077 R11: ffffed10258cd20e R12: 0000000000000001
> R13: 00000000000000a4 R14: 000000000000000c R15: ffff88812c6691ee
> FS: 00007fd0d6ff3740(0000) GS:ffff8883af180000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fd0d6dda290 CR3: 0000000104a62000 CR4: 00000000000006e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> iomap_apply+0x119/0x570
> iomap_bmap+0x124/0x150
> ext4_bmap+0x14f/0x250
> bmap+0x55/0x80
> do_vfs_ioctl+0x952/0xbd0
> __x64_sys_ioctl+0xc6/0x170
> do_syscall_64+0x33/0x40
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Above issue may happen as follows:
> bmap write
> bmap
> ext4_bmap
> iomap_bmap
> ext4_iomap_begin
> ext4_file_write_iter
> ext4_buffered_write_iter
> generic_perform_write
> ext4_da_write_begin
> ext4_da_write_inline_data_begin
> ext4_prepare_inline_data
> ext4_create_inline_data
> ext4_set_inode_flag(inode,
> EXT4_INODE_INLINE_DATA);
> if (WARN_ON_ONCE(ext4_has_inline_data(inode))) ->trigger bug_on
>
> To solved above issue hold inode lock in ext4_bamp.
^^^ ext4_bmap()
I checked the paths where bmap() kernel api can be called i.e. from jbd2/fc and
generic_swapfile_activate() (apart from ioctl())
For jbd2, it will be called with j_inode within bmap(), hence taking a inode lock
of the inode passed within ext4_bmap() (j_inode in this case) should be safe here.
Same goes with swapfile path as well.
However I feel maybe we should hold inode_lock_shared() since there is no
block/extent map layout changes that can happen via ext4_bmap().
Hence read lock is what IMO should be used here.
-ritesh
>
> Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx>
> ---
> fs/ext4/inode.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 53877ffe3c41..f4a95c80f644 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3142,13 +3142,15 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
> {
> struct inode *inode = mapping->host;
> journal_t *journal;
> + sector_t ret = 0;
> int err;
>
> + inode_lock(inode);
> /*
> * We can get here for an inline file via the FIBMAP ioctl
> */
> if (ext4_has_inline_data(inode))
> - return 0;
> + goto out;
>
> if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
> test_opt(inode->i_sb, DELALLOC)) {
> @@ -3187,10 +3189,14 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
> jbd2_journal_unlock_updates(journal);
>
> if (err)
> - return 0;
> + goto out;
> }
>
> - return iomap_bmap(mapping, block, &ext4_iomap_ops);
> + ret = iomap_bmap(mapping, block, &ext4_iomap_ops);
> +
> +out:
> + inode_unlock(inode);
> + return ret;
> }
>
> static int ext4_read_folio(struct file *file, struct folio *folio)
> --
> 2.31.1
>
