Currently on calling echo 3 > drop_caches on host machine, we see
FS corruption in the guest. This happens on Power machine where
blocksize < pagesize.
So as a temporary workaound don't enable dioread_nolock by default
for blocksize < pagesize until we identify the root cause.
Also emit a warning msg in case if this mount option is manually
enabled for blocksize < pagesize.
Reported-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
---
fs/ext4/super.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 27ab130a40d1..6873d9ffa352 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2186,6 +2186,14 @@ static int parse_options(char *options, struct super_block *sb,
}
}
#endif
+ if (test_opt(sb, DIOREAD_NOLOCK)) {
+ int blocksize =
+ BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
+ if (blocksize < PAGE_SIZE)
+ ext4_msg(sb, KERN_WARNING, "Warning: mounting with an "
+ "experimental mount option 'dioread_nolock' "
+ "for blocksize < PAGE_SIZE");
+ }
return 1;
}
@@ -3792,7 +3800,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
set_opt(sb, NO_UID32);
/* xattr user namespace & acls are now defaulted on */
set_opt(sb, XATTR_USER);
- set_opt(sb, DIOREAD_NOLOCK);
#ifdef CONFIG_EXT4_FS_POSIX_ACL
set_opt(sb, POSIX_ACL);
#endif
@@ -3842,6 +3849,10 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_li_wait_mult = EXT4_DEF_LI_WAIT_MULT;
blocksize = BLOCK_SIZE << le32_to_cpu(es->s_log_block_size);
+
+ if (blocksize == PAGE_SIZE)
+ set_opt(sb, DIOREAD_NOLOCK);
+
if (blocksize < EXT4_MIN_BLOCK_SIZE ||
blocksize > EXT4_MAX_BLOCK_SIZE) {
ext4_msg(sb, KERN_ERR,
--
2.20.1
