| From 2e9fa73a040462b81bfbfe56c0bc7ad2d30b446b Mon Sep 17 00:00:00 2001 |
| From: Theodore Ts'o <tytso@mit.edu> |
| Date: Tue, 30 Aug 2022 22:41:59 -0400 |
| Subject: [PATCH] fs/ext2: Ignore the large_dir incompat feature |
| |
| Recently, ext4 added the large_dir feature, which adds support for |
| a 3 level htree directory support. |
| |
| The GRUB supports existing file systems with htree directories by |
| ignoring their existence, and since the index nodes for the hash tree |
| look like deleted directory entries (by design), the GRUB can simply do |
| a brute force O(n) linear search of directories. The same is true for |
| 3 level deep htrees indicated by large_dir feature flag. |
| |
| Hence, it is safe for the GRUB to ignore the large_dir incompat feature. |
| |
| Fixes: https://savannah.gnu.org/bugs/?61606 |
| |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> |
| Upstream: 2e9fa73a040462b81bfbfe56c0bc7ad2d30b446b |
| Signed-off-by: Jens Maus <mail@jens-maus.de> |
| --- |
| grub-core/fs/ext2.c | 10 +++++++++- |
| 1 file changed, 9 insertions(+), 1 deletion(-) |
| |
| diff --git a/grub-core/fs/ext2.c b/grub-core/fs/ext2.c |
| index 0989e26e1..e1cc5e62a 100644 |
| --- a/grub-core/fs/ext2.c |
| +++ b/grub-core/fs/ext2.c |
| @@ -104,6 +104,7 @@ GRUB_MOD_LICENSE ("GPLv3+"); |
| #define EXT4_FEATURE_INCOMPAT_MMP 0x0100 |
| #define EXT4_FEATURE_INCOMPAT_FLEX_BG 0x0200 |
| #define EXT4_FEATURE_INCOMPAT_CSUM_SEED 0x2000 |
| +#define EXT4_FEATURE_INCOMPAT_LARGEDIR 0x4000 /* >2GB or 3 level htree */ |
| #define EXT4_FEATURE_INCOMPAT_ENCRYPT 0x10000 |
| |
| /* The set of back-incompatible features this driver DOES support. Add (OR) |
| @@ -129,10 +130,17 @@ GRUB_MOD_LICENSE ("GPLv3+"); |
| * checksummed filesystem. Safe to ignore for now since the |
| * driver doesn't support checksum verification. However, it |
| * has to be removed from this list if the support is added later. |
| + * large_dir: Not back-incompatible given that the GRUB ext2 driver does |
| + * not implement EXT2_FEATURE_COMPAT_DIR_INDEX. If the GRUB |
| + * eventually supports the htree feature (aka dir_index) |
| + * it should support 3 level htrees and then move |
| + * EXT4_FEATURE_INCOMPAT_LARGEDIR to |
| + * EXT2_DRIVER_SUPPORTED_INCOMPAT. |
| */ |
| #define EXT2_DRIVER_IGNORED_INCOMPAT ( EXT3_FEATURE_INCOMPAT_RECOVER \ |
| | EXT4_FEATURE_INCOMPAT_MMP \ |
| - | EXT4_FEATURE_INCOMPAT_CSUM_SEED) |
| + | EXT4_FEATURE_INCOMPAT_CSUM_SEED \ |
| + | EXT4_FEATURE_INCOMPAT_LARGEDIR) |
| |
| #define EXT3_JOURNAL_MAGIC_NUMBER 0xc03b3998U |
| |
| -- |
| 2.34.1 |
| |
