[PATCH] f2fs: walk around a panic caused by nrpages is not zero in clear_inode

[Yunlei He <heyunlei@huawei.com>]

I came across a panic twice:

[<ffffffc000088e70>] dump_backtrace+0x0/0x124
[<ffffffc000088fb4>] show_stack+0x14/0x1c
[<ffffffc000ce1c38>] dump_stack+0x20/0x28
[<ffffffc000cdfbd4>] panic+0x13c/0x258
[<ffffffc0001b2244>] clear_inode+0x8c/0xd4
[<ffffffc00030575c>] f2fs_evict_inode+0x194/0x3e0
[<ffffffc0001b30b4>] evict+0xa0/0x1cc
[<ffffffc0001b399c>] iput+0xe4/0x180
[<ffffffc0003274fc>] recover_fsync_data+0x6ec/0xe5c
[<ffffffc00030d420>] f2fs_fill_super+0xa5c/0xb9c
[<ffffffc00019cd00>] mount_bdev+0x1ac/0x1d4
[<ffffffc00030b66c>] f2fs_mount+0x14/0x1c
[<ffffffc00019d5e4>] mount_fs+0x3c/0x1bc
[<ffffffc0001b7560>] vfs_kern_mount+0x4c/0xf0
[<ffffffc0001b9970>] do_mount+0x218/0x960
[<ffffffc0001ba148>] SyS_mount+0x90/0xd0

Here, the nrpages in i_mapping in not zero but one. Maybe it's
caused by grabing cache page in truncate_partial_data_page. So
this patch walk around it.

Signed-off-by: Yunlei He <heyunlei@huawei.com>
---
 fs/f2fs/file.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 37c24be..7d1c3f3 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -561,6 +561,12 @@ static int truncate_partial_data_page(struct inode *inode, u64 from,
 	if (!offset && !cache_only)
 		return 0;
 
+	if (!offset && inode->i_state & I_FREEING)
+		return 0;
+
+	if (index > F2FS_I_SB(inode)->max_file_blocks)
+		return 0;
+
 	if (cache_only) {
 		page = f2fs_grab_cache_page(mapping, index, false);
 		if (page && PageUptodate(page))
-- 
1.9.1


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