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- 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
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