From: Ritesh Harjani <riteshh@xxxxxxxxxxxxx> commit 626b035b816b61a7a7b4d2205a6807e2f11a18c1 upstream. 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> Link: https://lore.kernel.org/r/20200327200744.12473-1-riteshh@xxxxxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 446158ab507dd..70796de7c4682 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2181,6 +2181,14 @@ 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; } @@ -3787,7 +3795,6 @@ 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 @@ -3837,6 +3844,10 @@ 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
