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ext4: fix clang build regression 

Arnd Bergmann <arnd@arndb.de>

As Stefan pointed out, I misremembered what clang can do specifically,
and it turns out that the variable-length array at the end of the
structure did not work (a flexible array would have worked here
but not solved the problem):

fs/ext4/mballoc.c:2303:17: error: fields must have a constant size:
'variable length array in structure' extension will never be supported
                ext4_grpblk_t counters[blocksize_bits + 2];

This reverts part of my previous patch, using a fixed-size array
again, but keeping the check for the array overflow.

Fixes: 2df2c3402f ("ext4: fix warning about stack corruption")
Reported-by: Stefan Agner <stefan@agner.ch>
Tested-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2017-08-14 08:29:18 -04:00
parent aae4e7a8bc
commit b80b32b6d5
1 changed files with 5 additions and 2 deletions
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7
fs/ext4/mballoc.c
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@ -2300,7 +2300,7 @@ static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v)
EXT4_MAX_BLOCK_LOG_SIZE); EXT4_MAX_BLOCK_LOG_SIZE);
struct sg { struct sg {
struct ext4_group_info info; struct ext4_group_info info;
ext4_grpblk_t counters[blocksize_bits + 2]; ext4_grpblk_t counters[EXT4_MAX_BLOCK_LOG_SIZE + 2];
} sg; } sg;
group--; group--;
@ -2309,6 +2309,9 @@ static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v)
" 2^0 2^1 2^2 2^3 2^4 2^5 2^6 " " 2^0 2^1 2^2 2^3 2^4 2^5 2^6 "
" 2^7 2^8 2^9 2^10 2^11 2^12 2^13 ]\n"); " 2^7 2^8 2^9 2^10 2^11 2^12 2^13 ]\n");
i = (blocksize_bits + 2) * sizeof(sg.info.bb_counters[0]) +
sizeof(struct ext4_group_info);
grinfo = ext4_get_group_info(sb, group); grinfo = ext4_get_group_info(sb, group);
/* Load the group info in memory only if not already loaded. */ /* Load the group info in memory only if not already loaded. */
if (unlikely(EXT4_MB_GRP_NEED_INIT(grinfo))) { if (unlikely(EXT4_MB_GRP_NEED_INIT(grinfo))) {
@ -2320,7 +2323,7 @@ static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v)
buddy_loaded = 1; buddy_loaded = 1;
} }
memcpy(&sg, ext4_get_group_info(sb, group), sizeof(sg)); memcpy(&sg, ext4_get_group_info(sb, group), i);
if (buddy_loaded) if (buddy_loaded)
ext4_mb_unload_buddy(&e4b); ext4_mb_unload_buddy(&e4b);