From 4260c4067fbba55a90037fe3ee32eff087749f83 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Wed, 24 Feb 2021 13:03:13 -0600 Subject: [PATCH] f2fs: Replace one-element array with flexible-array member MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. Refactor the code according to the use of a flexible-array member in struct f2fs_checkpoint, instead of a one-element arrays. Notice that a temporary pointer to void '*tmp_ptr' was used in order to fix the following errors when using a flexible array instead of a one element array in struct f2fs_checkpoint: CC [M] fs/f2fs/dir.o In file included from fs/f2fs/dir.c:13: fs/f2fs/f2fs.h: In function ‘__bitmap_ptr’: fs/f2fs/f2fs.h:2227:40: error: invalid use of flexible array member 2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32); | ^ fs/f2fs/f2fs.h:2227:49: error: invalid use of flexible array member 2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32); | ^ fs/f2fs/f2fs.h:2238:40: error: invalid use of flexible array member 2238 | return &ckpt->sit_nat_version_bitmap + offset; | ^ make[2]: *** [scripts/Makefile.build:287: fs/f2fs/dir.o] Error 1 make[1]: *** [scripts/Makefile.build:530: fs/f2fs] Error 2 make: *** [Makefile:1819: fs] Error 2 [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays Link: https://github.com/KSPP/linux/issues/79 Build-tested-by: kernel test robot Link: https://lore.kernel.org/lkml/603647e4.DeEFbl4eqljuwAUe%25lkp@intel.com/ Signed-off-by: Gustavo A. R. Silva Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/f2fs.h | 5 +++-- include/linux/f2fs_fs.h | 2 +- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index cccdfb1a40ab..99e243fd26d5 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -2215,6 +2215,7 @@ static inline block_t __cp_payload(struct f2fs_sb_info *sbi) static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag) { struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi); + void *tmp_ptr = &ckpt->sit_nat_version_bitmap; int offset; if (is_set_ckpt_flags(sbi, CP_LARGE_NAT_BITMAP_FLAG)) { @@ -2224,7 +2225,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag) * if large_nat_bitmap feature is enabled, leave checksum * protection for all nat/sit bitmaps. */ - return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32); + return tmp_ptr + offset + sizeof(__le32); } if (__cp_payload(sbi) > 0) { @@ -2235,7 +2236,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag) } else { offset = (flag == NAT_BITMAP) ? le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0; - return &ckpt->sit_nat_version_bitmap + offset; + return tmp_ptr + offset; } } diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h index c6cc0a566ef5..5487a80617a3 100644 --- a/include/linux/f2fs_fs.h +++ b/include/linux/f2fs_fs.h @@ -168,7 +168,7 @@ struct f2fs_checkpoint { unsigned char alloc_type[MAX_ACTIVE_LOGS]; /* SIT and NAT version bitmap */ - unsigned char sit_nat_version_bitmap[1]; + unsigned char sit_nat_version_bitmap[]; } __packed; #define CP_CHKSUM_OFFSET 4092 /* default chksum offset in checkpoint */