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Btrfs: add support for compat flags to btrfs
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This adds the necessary disk format for handling compatibility flags
in the future to handle disk format changes.  We have a compat_flags,
compat_ro_flags and incompat_flags set for the super block.  Compat
flags will be to hold the features that are compatible with older
versions of btrfs, compat_ro flags have features that are compatible
with older versions of btrfs if the fs is mounted read only, and
incompat_flags has features that are incompatible with older versions
of btrfs.  This also axes the compat_flags field for the inode and
just makes the flags field a 64bit field, and changes the root item
flags field to 64bit.

Signed-off-by: Josef Bacik <jbacik@redhat.com>
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Josef Bacik authored and Chris Mason committed Dec 2, 2008
1 parent 7a865e8 commit f2b636e
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Showing 2 changed files with 42 additions and 7 deletions.
28 changes: 21 additions & 7 deletions fs/btrfs/ctree.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -305,6 +305,9 @@ struct btrfs_super_block {
__le32 stripesize;
__le32 sys_chunk_array_size;
__le64 chunk_root_generation;
__le64 compat_flags;
__le64 compat_ro_flags;
__le64 incompat_flags;
u8 root_level;
u8 chunk_root_level;
u8 log_root_level;
Expand All @@ -313,6 +316,14 @@ struct btrfs_super_block {
u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
} __attribute__ ((__packed__));

/*
* Compat flags that we support. If any incompat flags are set other than the
* ones specified below then we will fail to mount
*/
#define BTRFS_FEATURE_COMPAT_SUPP 0x0
#define BTRFS_FEATURE_COMPAT_RO_SUPP 0x0
#define BTRFS_FEATURE_INCOMPAT_SUPP 0x0

/*
* A leaf is full of items. offset and size tell us where to find
* the item in the leaf (relative to the start of the data area)
Expand Down Expand Up @@ -433,8 +444,7 @@ struct btrfs_inode_item {
__le32 gid;
__le32 mode;
__le64 rdev;
__le16 flags;
__le16 compat_flags;
__le64 flags;

struct btrfs_timespec atime;
struct btrfs_timespec ctime;
Expand Down Expand Up @@ -462,7 +472,7 @@ struct btrfs_root_item {
__le64 byte_limit;
__le64 bytes_used;
__le64 last_snapshot;
__le32 flags;
__le64 flags;
__le32 refs;
struct btrfs_disk_key drop_progress;
u8 drop_level;
Expand Down Expand Up @@ -1116,9 +1126,7 @@ BTRFS_SETGET_FUNCS(inode_uid, struct btrfs_inode_item, uid, 32);
BTRFS_SETGET_FUNCS(inode_gid, struct btrfs_inode_item, gid, 32);
BTRFS_SETGET_FUNCS(inode_mode, struct btrfs_inode_item, mode, 32);
BTRFS_SETGET_FUNCS(inode_rdev, struct btrfs_inode_item, rdev, 64);
BTRFS_SETGET_FUNCS(inode_flags, struct btrfs_inode_item, flags, 16);
BTRFS_SETGET_FUNCS(inode_compat_flags, struct btrfs_inode_item,
compat_flags, 16);
BTRFS_SETGET_FUNCS(inode_flags, struct btrfs_inode_item, flags, 64);

static inline struct btrfs_timespec *
btrfs_inode_atime(struct btrfs_inode_item *inode_item)
Expand Down Expand Up @@ -1468,7 +1476,7 @@ BTRFS_SETGET_STACK_FUNCS(root_bytenr, struct btrfs_root_item, bytenr, 64);
BTRFS_SETGET_STACK_FUNCS(root_level, struct btrfs_root_item, level, 8);
BTRFS_SETGET_STACK_FUNCS(root_dirid, struct btrfs_root_item, root_dirid, 64);
BTRFS_SETGET_STACK_FUNCS(root_refs, struct btrfs_root_item, refs, 32);
BTRFS_SETGET_STACK_FUNCS(root_flags, struct btrfs_root_item, flags, 32);
BTRFS_SETGET_STACK_FUNCS(root_flags, struct btrfs_root_item, flags, 64);
BTRFS_SETGET_STACK_FUNCS(root_used, struct btrfs_root_item, bytes_used, 64);
BTRFS_SETGET_STACK_FUNCS(root_limit, struct btrfs_root_item, byte_limit, 64);
BTRFS_SETGET_STACK_FUNCS(root_last_snapshot, struct btrfs_root_item,
Expand Down Expand Up @@ -1510,6 +1518,12 @@ BTRFS_SETGET_STACK_FUNCS(super_root_dir, struct btrfs_super_block,
root_dir_objectid, 64);
BTRFS_SETGET_STACK_FUNCS(super_num_devices, struct btrfs_super_block,
num_devices, 64);
BTRFS_SETGET_STACK_FUNCS(super_compat_flags, struct btrfs_super_block,
compat_flags, 64);
BTRFS_SETGET_STACK_FUNCS(super_compat_ro_flags, struct btrfs_super_block,
compat_flags, 64);
BTRFS_SETGET_STACK_FUNCS(super_incompat_flags, struct btrfs_super_block,
incompat_flags, 64);

static inline unsigned long btrfs_leaf_data(struct extent_buffer *l)
{
Expand Down
21 changes: 21 additions & 0 deletions fs/btrfs/disk-io.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1434,6 +1434,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
u32 blocksize;
u32 stripesize;
u64 generation;
u64 features;
struct btrfs_key location;
struct buffer_head *bh;
struct btrfs_root *extent_root = kzalloc(sizeof(struct btrfs_root),
Expand Down Expand Up @@ -1586,6 +1587,26 @@ struct btrfs_root *open_ctree(struct super_block *sb,
goto fail_sb_buffer;
}

features = btrfs_super_incompat_flags(disk_super) &
~BTRFS_FEATURE_INCOMPAT_SUPP;
if (features) {
printk(KERN_ERR "BTRFS: couldn't mount because of "
"unsupported optional features (%Lx).\n",
features);
err = -EINVAL;
goto fail_sb_buffer;
}

features = btrfs_super_compat_ro_flags(disk_super) &
~BTRFS_FEATURE_COMPAT_RO_SUPP;
if (!(sb->s_flags & MS_RDONLY) && features) {
printk(KERN_ERR "BTRFS: couldn't mount RDWR because of "
"unsupported option features (%Lx).\n",
features);
err = -EINVAL;
goto fail_sb_buffer;
}

/*
* we need to start all the end_io workers up front because the
* queue work function gets called at interrupt time, and so it
Expand Down

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