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-rw-r--r--fs/ext4/ext4.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index d0f15ef..02ec44b 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1228,6 +1228,18 @@ struct ext4_group_info *ext4_get_group_info(struct super_block *sb,
return grp_info[indexv][indexh];
}
+/*
+ * Reading s_groups_count requires using smp_rmb() afterwards. See
+ * the locking protocol documented in the comments of ext4_group_add()
+ * in resize.c
+ */
+static inline ext4_group_t ext4_get_groups_count(struct super_block *sb)
+{
+ ext4_group_t ngroups = EXT4_SB(sb)->s_groups_count;
+
+ smp_rmb();
+ return ngroups;
+}
static inline ext4_group_t ext4_flex_group(struct ext4_sb_info *sbi,
ext4_group_t block_group)
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