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TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.cz:+] X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -3.01 X-Spam-Level: X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Queue-Id: ED5B55BD52 When a metadata block is referenced by multiple inodes and tracked by metadata bh infrastructure (which is forbidden and generally indicates filesystem corruption), it can happen that mmb_mark_buffer_dirty() is called for two different mmb structures in parallel. This can lead to a corruption of mmb linked list. Handle that situation gracefully (at least from mmb POV) by serializing on setting bh->b_mmb. Reported-by: Ruikai Peng Signed-off-by: Jan Kara --- fs/buffer.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) - fix inverted condition diff --git a/fs/buffer.c b/fs/buffer.c index d6e062c42a8d..b0b3792b1496 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -719,8 +719,15 @@ void mmb_mark_buffer_dirty(struct buffer_head *bh, mark_buffer_dirty(bh); if (!bh->b_mmb) { spin_lock(&mmb->lock); + /* + * For a corrupted filesystem with multiply claimed blocks this + * can fail. Avoid corrupting the linked list in that case. + */ + if (cmpxchg(&bh->b_mmb, NULL, mmb) != NULL) { + spin_unlock(&mmb->lock); + return; + } list_move_tail(&bh->b_assoc_buffers, &mmb->list); - bh->b_mmb = mmb; spin_unlock(&mmb->lock); } } -- 2.51.0