From: Qu Wenruo Date: Sat, 14 Mar 2026 00:00:38 +0000 (+1030) Subject: btrfs: check type flags in alloc_ordered_extent() X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=232770bcf3aa65ae83fd7389961fa651f09f7b3a;p=thirdparty%2Fkernel%2Flinux.git btrfs: check type flags in alloc_ordered_extent() Unlike other flags used in btrfs, BTRFS_ORDERED_* macros are different as they cannot be directly used as flags. They are defined as bit values, thus they should be utilized with bit operations, not directly with logical operations. Unfortunately sometimes I forgot this and passed the incorrect flags to alloc_ordered_extent() and hit weird bugs. Enhance the type checks in alloc_ordered_extent(): - Make sure there is one and only one bit set for exclusive type flags There are four exclusive type flags, REGULAR, NOCOW, PREALLOC and COMPRESSED. So introduce a new macro, BTRFS_ORDERED_EXCLUSIVE_FLAGS, to cover above flags. Add an ASSERT() to check one and only one of those exclusive flags can be set for alloc_ordered_extent(). - Re-order the type bit numbers to the end of the enum This is make it much harder to get a valid false negative. E.g., with the old code BTRFS_ORDERED_REGULAR starts at zero, we can have the following flags passing the bit uniqueness check: * BTRFS_ORDERED_NOCOW Be treated as BTRFS_ORDERED_REGULAR (1 == 1UL << 0). * BTRFS_ORDERED_PREALLOC Be treated as BTRFS_ORDERED_NOCOW (2 == 1UL << 1). * BTRFS_ORDERED_DIRECT Be treated as BTRFS_ORDERED_PREALLOC (4 == 1UL << 2). Now all those types start at 8, passing any of those bit numbers as flags directly will not pass the ASSERT(). - Add a static assert to avoid overflow To make sure all BTRFS_ORDERED_* flags can fit into an unsigned long. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c index 8405d07b49cdf..de6b60c522929 100644 --- a/fs/btrfs/ordered-data.c +++ b/fs/btrfs/ordered-data.c @@ -156,6 +156,19 @@ static struct btrfs_ordered_extent *alloc_ordered_extent( const bool is_nocow = (flags & ((1U << BTRFS_ORDERED_NOCOW) | (1U << BTRFS_ORDERED_PREALLOC))); + /* Only one type flag can be set. */ + ASSERT(has_single_bit_set(flags & BTRFS_ORDERED_EXCLUSIVE_FLAGS)); + + /* DIRECT cannot be set with COMPRESSED nor ENCODED. */ + if (test_bit(BTRFS_ORDERED_DIRECT, &flags)) { + ASSERT(!test_bit(BTRFS_ORDERED_COMPRESSED, &flags)); + ASSERT(!test_bit(BTRFS_ORDERED_ENCODED, &flags)); + } + + /* ENCODED must be set with COMPRESSED. */ + if (test_bit(BTRFS_ORDERED_ENCODED, &flags)) + ASSERT(test_bit(BTRFS_ORDERED_COMPRESSED, &flags)); + /* * For a NOCOW write we can free the qgroup reserve right now. For a COW * one we transfer the reserved space from the inode's iotree into the diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h index cd74c5ecfd678..03e12380a2fda 100644 --- a/fs/btrfs/ordered-data.h +++ b/fs/btrfs/ordered-data.h @@ -47,8 +47,25 @@ struct btrfs_ordered_sum { * IO is done and any metadata is inserted into the tree. */ enum { + /* Extra status bits for ordered extents */ + + /* Set when all the pages are written. */ + BTRFS_ORDERED_IO_DONE, + /* Set when removed from the tree. */ + BTRFS_ORDERED_COMPLETE, + /* We had an io error when writing this out. */ + BTRFS_ORDERED_IOERR, + /* Set when we have to truncate an extent. */ + BTRFS_ORDERED_TRUNCATED, + /* Used during fsync to track already logged extents. */ + BTRFS_ORDERED_LOGGED, + /* We have already logged all the csums of the ordered extent. */ + BTRFS_ORDERED_LOGGED_CSUM, + /* We wait for this extent to complete in the current transaction. */ + BTRFS_ORDERED_PENDING, + /* - * Different types for ordered extents, one and only one of the 4 types + * Different types for ordered extents, one and only one of these types * need to be set when creating ordered extent. * * REGULAR: For regular non-compressed COW write @@ -61,37 +78,27 @@ enum { BTRFS_ORDERED_PREALLOC, BTRFS_ORDERED_COMPRESSED, + /* Extra bit for encoded write, must be set with COMPRESSED. */ + BTRFS_ORDERED_ENCODED, + /* * Extra bit for direct io, can only be set for - * REGULAR/NOCOW/PREALLOC. No direct io for compressed extent. + * REGULAR/NOCOW/PREALLOC. Must not be set for COMPRESSED nor ENCODED. */ BTRFS_ORDERED_DIRECT, - /* Extra status bits for ordered extents */ - - /* set when all the pages are written */ - BTRFS_ORDERED_IO_DONE, - /* set when removed from the tree */ - BTRFS_ORDERED_COMPLETE, - /* We had an io error when writing this out */ - BTRFS_ORDERED_IOERR, - /* Set when we have to truncate an extent */ - BTRFS_ORDERED_TRUNCATED, - /* Used during fsync to track already logged extents */ - BTRFS_ORDERED_LOGGED, - /* We have already logged all the csums of the ordered extent */ - BTRFS_ORDERED_LOGGED_CSUM, - /* We wait for this extent to complete in the current transaction */ - BTRFS_ORDERED_PENDING, - /* BTRFS_IOC_ENCODED_WRITE */ - BTRFS_ORDERED_ENCODED, + BTRFS_ORDERED_NR_FLAGS, }; +static_assert(BTRFS_ORDERED_NR_FLAGS <= BITS_PER_LONG); + +/* One and only one flag can be set. */ +#define BTRFS_ORDERED_EXCLUSIVE_FLAGS ((1UL << BTRFS_ORDERED_REGULAR) | \ + (1UL << BTRFS_ORDERED_NOCOW) | \ + (1UL << BTRFS_ORDERED_PREALLOC) | \ + (1UL << BTRFS_ORDERED_COMPRESSED)) /* BTRFS_ORDERED_* flags that specify the type of the extent. */ -#define BTRFS_ORDERED_TYPE_FLAGS ((1UL << BTRFS_ORDERED_REGULAR) | \ - (1UL << BTRFS_ORDERED_NOCOW) | \ - (1UL << BTRFS_ORDERED_PREALLOC) | \ - (1UL << BTRFS_ORDERED_COMPRESSED) | \ +#define BTRFS_ORDERED_TYPE_FLAGS (BTRFS_ORDERED_EXCLUSIVE_FLAGS | \ (1UL << BTRFS_ORDERED_DIRECT) | \ (1UL << BTRFS_ORDERED_ENCODED))