From: Joshua Ashton <joshua@froggi.es>
Date: Sun, 13 Aug 2023 15:53:45 +0000 (+0100)
Subject: bcachefs: Lower BCH_NAME_MAX to 512
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=a125c0742ccb0b5f2bc84f3f1a8bcee173c1130d;p=linux.git

bcachefs: Lower BCH_NAME_MAX to 512

To ensure we aren't shooting ourselves in the foot after merge for
potentially doing future revisions for dirent or for storing multiple
names for casefolding, limit this to 512 for now.

Previously this define was linked to the max size a d_name in
bch_dirent could be.

Signed-off-by: Joshua Ashton <joshua@froggi.es>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---

diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h
index 5ec218ee35694..23bae622309c5 100644
--- a/fs/bcachefs/bcachefs_format.h
+++ b/fs/bcachefs/bcachefs_format.h
@@ -916,9 +916,7 @@ struct bch_dirent {
 #define DT_SUBVOL	16
 #define BCH_DT_MAX	17
 
-#define BCH_NAME_MAX	((unsigned) (U8_MAX * sizeof(__u64) -		\
-			 sizeof(struct bkey) -				\
-			 offsetof(struct bch_dirent, d_name)))
+#define BCH_NAME_MAX	512
 
 /* Xattrs */
 
diff --git a/fs/bcachefs/dirent.c b/fs/bcachefs/dirent.c
index 6f9eb88c7dba9..a7559ab03802c 100644
--- a/fs/bcachefs/dirent.c
+++ b/fs/bcachefs/dirent.c
@@ -115,7 +115,11 @@ int bch2_dirent_invalid(const struct bch_fs *c, struct bkey_s_c k,
 		return -BCH_ERR_invalid_bkey;
 	}
 
-	if (d_name.len > BCH_NAME_MAX) {
+	/*
+	 * Check new keys don't exceed the max length
+	 * (older keys may be larger.)
+	 */
+	if ((flags & BKEY_INVALID_COMMIT) && d_name.len > BCH_NAME_MAX) {
 		prt_printf(err, "dirent name too big (%u > %u)",
 		       d_name.len, BCH_NAME_MAX);
 		return -BCH_ERR_invalid_bkey;