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btrfs: convert to multigrain timestamps

Enable multigrain timestamps, which should ensure that there is an
apparent change to the timestamp whenever it has been written after
being actively observed via getattr.

Beyond enabling the FS_MGTIME flag, this patch eliminates
update_time_for_write, which goes to great pains to avoid in-memory
stores. Just have it overwrite the timestamps unconditionally.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Acked-by: David Sterba <dsterba@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230807-mgctime-v7-13-d1dec143a704@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Jeff Layton 2023-08-07 15:38:44 -04:00 committed by Christian Brauner
parent 0269b58586
commit 50e9ceef1d
No known key found for this signature in database
GPG key ID: 91C61BC06578DCA2
2 changed files with 7 additions and 22 deletions

View file

@ -1106,25 +1106,6 @@ void btrfs_check_nocow_unlock(struct btrfs_inode *inode)
btrfs_drew_write_unlock(&inode->root->snapshot_lock);
}
static void update_time_for_write(struct inode *inode)
{
struct timespec64 now, ctime;
if (IS_NOCMTIME(inode))
return;
now = current_time(inode);
if (!timespec64_equal(&inode->i_mtime, &now))
inode->i_mtime = now;
ctime = inode_get_ctime(inode);
if (!timespec64_equal(&ctime, &now))
inode_set_ctime_to_ts(inode, now);
if (IS_I_VERSION(inode))
inode_inc_iversion(inode);
}
static int btrfs_write_check(struct kiocb *iocb, struct iov_iter *from,
size_t count)
{
@ -1156,7 +1137,10 @@ static int btrfs_write_check(struct kiocb *iocb, struct iov_iter *from,
* need to start yet another transaction to update the inode as we will
* update the inode when we finish writing whatever data we write.
*/
update_time_for_write(inode);
if (!IS_NOCMTIME(inode)) {
inode->i_mtime = inode_set_ctime_current(inode);
inode_inc_iversion(inode);
}
start_pos = round_down(pos, fs_info->sectorsize);
oldsize = i_size_read(inode);

View file

@ -2144,7 +2144,7 @@ static struct file_system_type btrfs_fs_type = {
.name = "btrfs",
.mount = btrfs_mount,
.kill_sb = btrfs_kill_super,
.fs_flags = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
.fs_flags = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA | FS_MGTIME,
};
static struct file_system_type btrfs_root_fs_type = {
@ -2152,7 +2152,8 @@ static struct file_system_type btrfs_root_fs_type = {
.name = "btrfs",
.mount = btrfs_mount_root,
.kill_sb = btrfs_kill_super,
.fs_flags = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA | FS_ALLOW_IDMAP,
.fs_flags = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA |
FS_ALLOW_IDMAP | FS_MGTIME,
};
MODULE_ALIAS_FS("btrfs");