On 09/04/2021 02:33, Boris Burkov wrote:
The tree checker currently rejects unrecognized flags when it reads btrfs_inode_item. Practically, this means that adding a new flag makes the change backwards incompatible if the flag is ever set on a file.
Take up one of the 4 reserved u64 fields in the btrfs_inode_item as a new "compat_flags". These flags are zero on inode creation in btrfs and mkfs and are ignored by an older kernel, so it should be safe to use them in this way.
I don't see an incompt flags check during mount, how does this patch will handle if you mount a disk with an older on-disk btrfs_inode_item data structure which has no compat_flags?
Why not update the tree checker (need to fix stable kernel as well) and inode flags, so that we spare u64 space in the btrfs_inode_item?
Also, I think we need the incompt flags to check during mount. Thanks, Anand
Signed-off-by: Boris Burkov <boris@xxxxxx> --- fs/btrfs/btrfs_inode.h | 1 + fs/btrfs/ctree.h | 2 ++ fs/btrfs/delayed-inode.c | 2 ++ fs/btrfs/inode.c | 3 +++ fs/btrfs/ioctl.c | 7 ++++--- fs/btrfs/tree-log.c | 1 + include/uapi/linux/btrfs_tree.h | 7 ++++++- 7 files changed, 19 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index c652e19ad74e..e8dbc8e848ce 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -191,6 +191,7 @@ struct btrfs_inode {/* flags field from the on disk inode */u32 flags; + u64 compat_flags;/** Counters to keep track of the number of extent item's we may use due diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index f2fd73e58ee6..d633c563164b 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1754,6 +1754,7 @@ 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, 64); +BTRFS_SETGET_FUNCS(inode_compat_flags, struct btrfs_inode_item, compat_flags, 64); BTRFS_SETGET_STACK_FUNCS(stack_inode_generation, struct btrfs_inode_item, generation, 64); BTRFS_SETGET_STACK_FUNCS(stack_inode_sequence, struct btrfs_inode_item, @@ -1771,6 +1772,7 @@ BTRFS_SETGET_STACK_FUNCS(stack_inode_gid, struct btrfs_inode_item, gid, 32); BTRFS_SETGET_STACK_FUNCS(stack_inode_mode, struct btrfs_inode_item, mode, 32); BTRFS_SETGET_STACK_FUNCS(stack_inode_rdev, struct btrfs_inode_item, rdev, 64); BTRFS_SETGET_STACK_FUNCS(stack_inode_flags, struct btrfs_inode_item, flags, 64); +BTRFS_SETGET_STACK_FUNCS(stack_inode_compat_flags, struct btrfs_inode_item, compat_flags, 64); BTRFS_SETGET_FUNCS(timespec_sec, struct btrfs_timespec, sec, 64); BTRFS_SETGET_FUNCS(timespec_nsec, struct btrfs_timespec, nsec, 32); BTRFS_SETGET_STACK_FUNCS(stack_timespec_sec, struct btrfs_timespec, sec, 64); diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c index 1a88f6214ebc..ef4e0265dbe3 100644 --- a/fs/btrfs/delayed-inode.c +++ b/fs/btrfs/delayed-inode.c @@ -1718,6 +1718,7 @@ static void fill_stack_inode_item(struct btrfs_trans_handle *trans, btrfs_set_stack_inode_transid(inode_item, trans->transid); btrfs_set_stack_inode_rdev(inode_item, inode->i_rdev); btrfs_set_stack_inode_flags(inode_item, BTRFS_I(inode)->flags); + btrfs_set_stack_inode_compat_flags(inode_item, BTRFS_I(inode)->compat_flags); btrfs_set_stack_inode_block_group(inode_item, 0);btrfs_set_stack_timespec_sec(&inode_item->atime,@@ -1776,6 +1777,7 @@ int btrfs_fill_inode(struct inode *inode, u32 *rdev) inode->i_rdev = 0; *rdev = btrfs_stack_inode_rdev(inode_item); BTRFS_I(inode)->flags = btrfs_stack_inode_flags(inode_item); + BTRFS_I(inode)->compat_flags = btrfs_stack_inode_compat_flags(inode_item);inode->i_atime.tv_sec = btrfs_stack_timespec_sec(&inode_item->atime);inode->i_atime.tv_nsec = btrfs_stack_timespec_nsec(&inode_item->atime); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 1e0e20ad25e4..3aa96ec27045 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -3627,6 +3627,7 @@ static int btrfs_read_locked_inode(struct inode *inode,BTRFS_I(inode)->index_cnt = (u64)-1;BTRFS_I(inode)->flags = btrfs_inode_flags(leaf, inode_item); + BTRFS_I(inode)->compat_flags = btrfs_inode_compat_flags(leaf, inode_item);cache_index:/* @@ -3793,6 +3794,7 @@ static void fill_inode_item(struct btrfs_trans_handle *trans, btrfs_set_token_inode_transid(&token, item, trans->transid); btrfs_set_token_inode_rdev(&token, item, inode->i_rdev); btrfs_set_token_inode_flags(&token, item, BTRFS_I(inode)->flags); + btrfs_set_token_inode_compat_flags(&token, item, BTRFS_I(inode)->compat_flags); btrfs_set_token_inode_block_group(&token, item, 0); }@@ -8859,6 +8861,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)ei->defrag_bytes = 0; ei->disk_i_size = 0; ei->flags = 0; + ei->compat_flags = 0; ei->csum_bytes = 0; ei->index_cnt = (u64)-1; ei->dir_index = 0; diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 3415a9f06c81..2c9cbd2642b1 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -102,8 +102,9 @@ static unsigned int btrfs_mask_fsflags_for_type(struct inode *inode, * Export internal inode flags to the format expected by the FS_IOC_GETFLAGS * ioctl. */ -static unsigned int btrfs_inode_flags_to_fsflags(unsigned int flags) +static unsigned int btrfs_inode_flags_to_fsflags(struct btrfs_inode *binode) { + unsigned int flags = binode->flags; unsigned int iflags = 0;if (flags & BTRFS_INODE_SYNC)@@ -156,7 +157,7 @@ void btrfs_sync_inode_flags_to_i_flags(struct inode *inode) static int btrfs_ioctl_getflags(struct file *file, void __user *arg) { struct btrfs_inode *binode = BTRFS_I(file_inode(file)); - unsigned int flags = btrfs_inode_flags_to_fsflags(binode->flags); + unsigned int flags = btrfs_inode_flags_to_fsflags(binode);if (copy_to_user(arg, &flags, sizeof(flags)))return -EFAULT; @@ -228,7 +229,7 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)btrfs_inode_lock(inode, 0);fsflags = btrfs_mask_fsflags_for_type(inode, fsflags); - old_fsflags = btrfs_inode_flags_to_fsflags(binode->flags); + old_fsflags = btrfs_inode_flags_to_fsflags(binode);ret = vfs_ioc_setflags_prepare(inode, old_fsflags, fsflags);if (ret) diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 72c4b66ed516..fed638f995ba 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -3944,6 +3944,7 @@ static void fill_inode_item(struct btrfs_trans_handle *trans, btrfs_set_token_inode_transid(&token, item, trans->transid); btrfs_set_token_inode_rdev(&token, item, inode->i_rdev); btrfs_set_token_inode_flags(&token, item, BTRFS_I(inode)->flags); + btrfs_set_token_inode_compat_flags(&token, item, BTRFS_I(inode)->compat_flags); btrfs_set_token_inode_block_group(&token, item, 0); }diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.hindex 58d7cff9afb1..ae25280316bd 100644 --- a/include/uapi/linux/btrfs_tree.h +++ b/include/uapi/linux/btrfs_tree.h @@ -574,11 +574,16 @@ struct btrfs_inode_item { /* modification sequence number for NFS */ __le64 sequence;+ /*+ * flags which aren't checked for corruption at mount + * and can be added in a backwards compatible way + */ + __le64 compat_flags; /* * a little future expansion, for more than this we can * just grow the inode item and version it */ - __le64 reserved[4]; + __le64 reserved[3]; struct btrfs_timespec atime; struct btrfs_timespec ctime; struct btrfs_timespec mtime;
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