bcachefs: Don't delete open files in online fsck

If a file is unlinked but still open, we don't want online fsck to
delete it - or fun inconsistencies will happen.

https://github.com/koverstreet/bcachefs/issues/727Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/fs.c

@@ -177,6 +177,14 @@ static unsigned bch2_inode_hash(subvol_inum inum)
 	return jhash_3words(inum.subvol, inum.inum >> 32, inum.inum, JHASH_INITVAL);
 }
 
+struct bch_inode_info *__bch2_inode_hash_find(struct bch_fs *c, subvol_inum inum)
+{
+	return to_bch_ei(ilookup5_nowait(c->vfs_sb,
+					 bch2_inode_hash(inum),
+					 bch2_iget5_test,
+					 &inum));
+}
+
 static struct bch_inode_info *bch2_inode_insert(struct bch_fs *c, struct bch_inode_info *inode)
 {
 	subvol_inum inum = inode_inum(inode);

fs/bcachefs/fs.h

@@ -56,6 +56,8 @@ static inline subvol_inum inode_inum(struct bch_inode_info *inode)
 	};
 }
 
+struct bch_inode_info *__bch2_inode_hash_find(struct bch_fs *, subvol_inum);
+
 /*
  * Set if we've gotten a btree error for this inode, and thus the vfs inode and
  * btree inode may be inconsistent:
@@ -194,6 +196,11 @@ int bch2_vfs_init(void);
 
 #define bch2_inode_update_after_write(_trans, _inode, _inode_u, _fields)	({ do {} while (0); })
 
+static inline struct bch_inode_info *__bch2_inode_hash_find(struct bch_fs *c, subvol_inum inum)
+{
+	return NULL;
+}
+
 static inline void bch2_evict_subvolume_inodes(struct bch_fs *c,
 					       snapshot_id_list *s) {}
 static inline void bch2_vfs_exit(void) {}

fs/bcachefs/fsck.c

@@ -8,6 +8,7 @@
 #include "darray.h"
 #include "dirent.h"
 #include "error.h"
+#include "fs.h"
 #include "fs-common.h"
 #include "fsck.h"
 #include "inode.h"
@@ -962,6 +963,22 @@ static int check_inode_dirent_inode(struct btree_trans *trans, struct bkey_s_c i
 	return ret;
 }
 
+static bool bch2_inode_open(struct bch_fs *c, struct bpos p)
+{
+	subvol_inum inum = {
+		.subvol = snapshot_t(c, p.snapshot)->subvol,
+		.inum	= p.offset,
+	};
+
+	/* snapshot tree corruption, can't safely delete */
+	if (!inum.subvol) {
+		bch_err_ratelimited(c, "%s(): snapshot %u has no subvol", __func__, p.snapshot);
+		return true;
+	}
+
+	return __bch2_inode_hash_find(c, inum) != NULL;
+}
+
 static int check_inode(struct btree_trans *trans,
 		       struct btree_iter *iter,
 		       struct bkey_s_c k,
@@ -1040,6 +1057,7 @@ static int check_inode(struct btree_trans *trans,
 	}
 
 	if (u.bi_flags & BCH_INODE_unlinked &&
+	    !bch2_inode_open(c, k.k->p) &&
 	    (!c->sb.clean ||
 	     fsck_err(trans, inode_unlinked_but_clean,
 		      "filesystem marked clean, but inode %llu unlinked",