On 2022/6/15 23:21, Ritesh Harjani wrote:
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
Thank you for your advice.
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.
