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Commit fd47d3e1 authored by Behan Webster's avatar Behan Webster Committed by Theodore Ts'o
Browse files

jbd2: remove VLAIS usage from JBD2 code 



The use of variable length arrays in structs (VLAIS) in the Linux Kernel code
precludes the use of compilers which don't implement VLAIS (for instance the
Clang compiler). Since ctx is always a 32-bit CRC, hard coding a size of 4
bytes accomplishes the same thing without the use of VLAIS. This is the same
technique already employed in fs/ext4/ext4.h

Signed-off-by: default avatarMark Charlebois <charlebm@gmail.com>
Signed-off-by: default avatarBehan Webster <behanw@converseincode.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 37be2f59

include/linux/jbd2.h

+7 −1
Original line number Diff line number Diff line
@@ -1302,15 +1302,21 @@ static inline int jbd_space_needed(journal_t *journal) 


extern int jbd_blocks_per_page(struct inode *inode);



/* JBD uses a CRC32 checksum */

#define JBD_MAX_CHECKSUM_SIZE 4



static inline u32 jbd2_chksum(journal_t *journal, u32 crc,

			      const void *address, unsigned int length)

{

	struct {

		struct shash_desc shash;

		char ctx[crypto_shash_descsize(journal->j_chksum_driver)];

		char ctx[JBD_MAX_CHECKSUM_SIZE];

	} desc;

	int err;



	BUG_ON(crypto_shash_descsize(journal->j_chksum_driver) >

		JBD_MAX_CHECKSUM_SIZE);



	desc.shash.tfm = journal->j_chksum_driver;

	desc.shash.flags = 0;

	*(u32 *)desc.ctx = crc;