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ext4: don't set dioread_nolock by default for blocksize < pagesize 

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@linux.ibm.com>
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20200327200744.12473-1-riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Ritesh Harjani 2020-03-28 01:37:44 +05:30 committed by Theodore Ts'o
parent c8980e1980
commit 626b035b81
1 changed files with 12 additions and 1 deletions
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13
fs/ext4/super.c
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@ -2187,6 +2187,14 @@ 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;
}
@ -3793,7 +3801,6 @@ 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
@ -3843,6 +3850,10 @@ 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,