bcachefs: Flag inodes that had btree update errors

On write error, the vfs inode's i_size may be inconsistent with the
btree inode's i_size - flag this so we don't have spurious assertions.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/fs-io.c

@@ -994,6 +994,8 @@ static void bch2_writepage_io_done(struct closure *cl)
 	unsigned i;
 
 	if (io->op.error) {
+		set_bit(EI_INODE_ERROR, &io->inode->ei_flags);
+
 		bio_for_each_segment_all(bvec, bio, iter) {
 			struct bch_page_state *s;
 
@@ -1916,7 +1918,13 @@ static long bch2_dio_write_loop(struct dio_write *dio)
 
 		bio_for_each_segment_all(bv, bio, iter)
 			put_page(bv->bv_page);
-		if (!dio->iter.count || dio->op.error)
+
+		if (dio->op.error) {
+			set_bit(EI_INODE_ERROR, &inode->ei_flags);
+			break;
+		}
+
+		if (!dio->iter.count)
 			break;
 
 		bio_reset(bio, NULL, REQ_OP_WRITE);
@@ -2306,7 +2314,8 @@ int bch2_truncate(struct bch_inode_info *inode, struct iattr *iattr)
 	if (ret)
 		goto err;
 
-	BUG_ON(inode->v.i_size < inode_u.bi_size);
+	WARN_ON(!test_bit(EI_INODE_ERROR, &inode->ei_flags) &&
+		inode->v.i_size < inode_u.bi_size);
 
 	if (iattr->ia_size > inode->v.i_size) {
 		ret = bch2_extend(inode, &inode_u, iattr);

fs/bcachefs/fs.c

@@ -1161,6 +1161,7 @@ static void bch2_vfs_inode_init(struct bch_fs *c,
 	inode->v.i_generation	= bi->bi_generation;
 	inode->v.i_size		= bi->bi_size;
 
+	inode->ei_flags		= 0;
 	inode->ei_journal_seq	= 0;
 	inode->ei_quota_reserved = 0;
 	inode->ei_str_hash	= bch2_hash_info_init(c, bi);

fs/bcachefs/fs.h

@@ -33,6 +33,7 @@ void bch2_pagecache_block_get(struct pagecache_lock *);
 
 struct bch_inode_info {
 	struct inode		v;
+	unsigned long		ei_flags;
 
 	struct mutex		ei_update_lock;
 	u64			ei_journal_seq;
@@ -49,6 +50,12 @@ struct bch_inode_info {
 	struct bch_inode_unpacked ei_inode;
 };
 
+/*
+ * Set if we've gotten a btree error for this inode, and thus the vfs inode and
+ * btree inode may be inconsistent:
+ */
+#define EI_INODE_ERROR			0
+
 #define to_bch_ei(_inode)					\
 	container_of_or_null(_inode, struct bch_inode_info, v)