5.4-stable review patch. If anyone has any objections, please let me know.
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From: David Howells dhowells@redhat.com
[ Upstream commit 5f7a07646655fb4108da527565dcdc80124b14c4 ]
If a directory has a block with only ".__afsXXXX" files in it (from uncompleted silly-rename), these .__afsXXXX files are skipped but without advancing the file position in the dir_context. This leads to afs_dir_iterate() repeating the block again and again.
Fix this by making the code that skips the .__afsXXXX file also manually advance the file position.
The symptoms are a soft lookup:
watchdog: BUG: soft lockup - CPU#3 stuck for 52s! [check:5737] ... RIP: 0010:afs_dir_iterate_block+0x39/0x1fd ... ? watchdog_timer_fn+0x1a6/0x213 ... ? asm_sysvec_apic_timer_interrupt+0x16/0x20 ? afs_dir_iterate_block+0x39/0x1fd afs_dir_iterate+0x10a/0x148 afs_readdir+0x30/0x4a iterate_dir+0x93/0xd3 __do_sys_getdents64+0x6b/0xd4
This is almost certainly the actual fix for:
https://bugzilla.kernel.org/show_bug.cgi?id=218496
Fixes: 57e9d49c5452 ("afs: Hide silly-rename files from userspace") Signed-off-by: David Howells dhowells@redhat.com Link: https://lore.kernel.org/r/786185.1708694102@warthog.procyon.org.uk Reviewed-by: Marc Dionne marc.dionne@auristor.com cc: Marc Dionne marc.dionne@auristor.com cc: Markus Suvanto markus.suvanto@gmail.com cc: linux-afs@lists.infradead.org Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/afs/dir.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/afs/dir.c b/fs/afs/dir.c index 8bed9df092301..1ada9b9cb21ec 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -426,8 +426,10 @@ static int afs_dir_iterate_block(struct afs_vnode *dvnode, dire->u.name[0] == '.' && ctx->actor != afs_lookup_filldir && ctx->actor != afs_lookup_one_filldir && - memcmp(dire->u.name, ".__afs", 6) == 0) + memcmp(dire->u.name, ".__afs", 6) == 0) { + ctx->pos = blkoff + next * sizeof(union afs_xdr_dirent); continue; + }
/* found the next entry */ if (!dir_emit(ctx, dire->u.name, nlen,