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btrfs-progs: fix gcc9 warning and potentially unaligned access to dev stats 

GCC9 9.1.1 with -Waddress-of-packed-member warns about passing an
unaligned pointer from btrfs_dev_stats_values. It is up to the caller to
access the array properly, which does happen in print_dev_stats.

In file included from print-tree.c:24:
ctree.h: In function ‘btrfs_dev_stats_values’:
ctree.h:2408:9: warning: taking address of packed member of ‘struct btrfs_dev_stats_item’ may result in an unaligned pointer value [-Waddress-of-packed-member]
 2408 |  return p->values;

Drop the helper as print-tree.c is the only user and access the dev stat
values using the unaligned helper.

Signed-off-by: David Sterba <dsterba@suse.com>
master
David Sterba 2019-06-11 15:27:24 +02:00
parent 2570cff076
commit 691656abdc
2 changed files with 16 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
ctree.h
View File

@ -2395,19 +2395,6 @@ static inline struct btrfs_disk_balance_args* btrfs_balance_item_sys(
return &p->sys;
}
/*
* btrfs_dev_stats_item helper, returns pointer to the raw array, do the
* endianness conversion, @dsi is offset to eb data
*/
static inline __le64* btrfs_dev_stats_values(struct extent_buffer *eb,
struct btrfs_dev_stats_item *dsi)
{
unsigned long offset = (unsigned long)dsi;
struct btrfs_dev_stats_item *p;
p = (struct btrfs_dev_stats_item *)(eb->data + offset);
return p->values;
}
/*
* this returns the number of bytes used by the item on disk, minus the
* size of any extent headers. If a file is compressed on disk, this is

24
print-tree.c
View File

@ -953,24 +953,32 @@ static void print_balance_item(struct extent_buffer *eb,
static void print_dev_stats(struct extent_buffer *eb,
struct btrfs_dev_stats_item *stats, u32 size)
{
int i;
struct btrfs_dev_stats_item *item;
const unsigned long offset = (unsigned long)stats;
u32 known = BTRFS_DEV_STAT_VALUES_MAX * sizeof(__le64);
__le64 *values = btrfs_dev_stats_values(eb, stats);
int i;
item = (struct btrfs_dev_stats_item *)(eb->data + offset);
printf("\t\tdevice stats\n");
printf("\t\twrite_errs %llu read_errs %llu flush_errs %llu corruption_errs %llu generation %llu\n",
(unsigned long long)le64_to_cpu(values[BTRFS_DEV_STAT_WRITE_ERRS]),
(unsigned long long)le64_to_cpu(values[BTRFS_DEV_STAT_READ_ERRS]),
(unsigned long long)le64_to_cpu(values[BTRFS_DEV_STAT_FLUSH_ERRS]),
(unsigned long long)le64_to_cpu(values[BTRFS_DEV_STAT_CORRUPTION_ERRS]),
(unsigned long long)le64_to_cpu(values[BTRFS_DEV_STAT_GENERATION_ERRS]));
(unsigned long long)get_unaligned_le64(
&item->values[BTRFS_DEV_STAT_WRITE_ERRS]),
(unsigned long long)get_unaligned_le64(
&item->values[BTRFS_DEV_STAT_READ_ERRS]),
(unsigned long long)get_unaligned_le64(
&item->values[BTRFS_DEV_STAT_FLUSH_ERRS]),
(unsigned long long)get_unaligned_le64(
&item->values[BTRFS_DEV_STAT_CORRUPTION_ERRS]),
(unsigned long long)get_unaligned_le64(
&item->values[BTRFS_DEV_STAT_GENERATION_ERRS]));
if (known < size) {
printf("\t\tunknown stats item bytes %u", size - known);
for (i = BTRFS_DEV_STAT_VALUES_MAX; i * sizeof(__le64) < size; i++) {
printf("\t\tunknown item %u offset %zu value %llu\n",
i, i * sizeof(__le64),
(unsigned long long)le64_to_cpu(values[i]));
(unsigned long long)le64_to_cpu(&item->values[i]));
}
}
}