FS_COW_FL and FS_NOCOW_FL were newly introduced to control per file
COW in btrfs, but FS_NOCOW_FL is sufficient.
The fact is we don't have corresponding BTRFS_INODE_COW flag.
COW is default, and FS_NOCOW_FL can be used to switch off COW for
a single file.
If we mount btrfs with nodatacow, a newly created file will be set with
the FS_NOCOW_FL flag. So to turn on COW for it, we can just clear the
FS_NOCOW_FL flag.
Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
---
fs/btrfs/ioctl.c | 15 ++++++---------
include/linux/fs.h | 1 -
2 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index f580a3a..3240dd9 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -144,16 +144,13 @@ static int check_flags(unsigned int flags)
if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
FS_NOATIME_FL | FS_NODUMP_FL | \
FS_SYNC_FL | FS_DIRSYNC_FL | \
- FS_NOCOMP_FL | FS_COMPR_FL | \
- FS_NOCOW_FL | FS_COW_FL))
+ FS_NOCOMP_FL | FS_COMPR_FL |
+ FS_NOCOW_FL))
return -EOPNOTSUPP;
if ((flags & FS_NOCOMP_FL) && (flags & FS_COMPR_FL))
return -EINVAL;
- if ((flags & FS_NOCOW_FL) && (flags & FS_COW_FL))
- return -EINVAL;
-
return 0;
}
@@ -218,6 +215,10 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
ip->flags |= BTRFS_INODE_DIRSYNC;
else
ip->flags &= ~BTRFS_INODE_DIRSYNC;
+ if (flags & FS_NOCOW_FL)
+ ip->flags |= BTRFS_INODE_NODATACOW;
+ else
+ ip->flags &= ~BTRFS_INODE_NODATACOW;
/*
* The COMPRESS flag can only be changed by users, while the NOCOMPRESS
@@ -231,10 +232,6 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
ip->flags |= BTRFS_INODE_COMPRESS;
ip->flags &= ~BTRFS_INODE_NOCOMPRESS;
}
- if (flags & FS_NOCOW_FL)
- ip->flags |= BTRFS_INODE_NODATACOW;
- else if (flags & FS_COW_FL)
- ip->flags &= ~BTRFS_INODE_NODATACOW;
trans = btrfs_join_transaction(root, 1);
BUG_ON(IS_ERR(trans));
diff --git a/include/linux/fs.h b/include/linux/fs.h
index de9dd81..56a4141 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -365,7 +365,6 @@ struct inodes_stat_t {
#define FS_EXTENT_FL 0x00080000 /* Extents */
#define FS_DIRECTIO_FL 0x00100000 /* Use direct i/o */
#define FS_NOCOW_FL 0x00800000 /* Do not cow file */
-#define FS_COW_FL 0x02000000 /* Cow file */
#define FS_RESERVED_FL 0x80000000 /* reserved for ext2 lib */
#define FS_FL_USER_VISIBLE 0x0003DFFF /* User visible flags */
--
1.7.3.1
--
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