On 7.02.19 г. 18:54 ч., Josef Bacik wrote:
> We've been seeing errors on our build servers related to failing to
> inherit inode properties. This is because we do not pre-reserve space
> for them, instead trying to reserve space with NO_FLUSH at inheritance
> time. NO_FLUSH can transiently fail, but we'll still complain. It's
Put one or two sentences describing the implications of
BTRFS_RESERVE_NO_FLUSH. I.e that it NO_FLUSH won't try to flush current
metadata reservation which could result in the said transient failure.
Just to give a bit more context for someone who might be reading the
commit message in the future.
> just an extra credit, so simply add that to the places that call
> btrfs_new_inode and call it good enough.
>
> Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/inode.c | 78 ++++++++++++++++++++++----------------------------------
> fs/btrfs/ioctl.c | 27 ++++++++++++--------
> 2 files changed, 46 insertions(+), 59 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 6126de9b8b9c..0da4a9d6d9fe 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -59,6 +59,14 @@ struct btrfs_dio_data {
> int overwrite;
> };
>
> +/*
> + * 2 for inode item and ref
> + * 2 for dir items
> + * 1 for xattr if selinux is on
> + * 1 for inherited properties
> + */
> +#define BTRFS_NEW_INODE_ITEMS 6
Rather than having scattered defines I'd much prefer if we have an enum
and over time add all distinct reservations to that enum and change
btrfs_start_transaction's interface to take this enum. It will be much
more descriptive than having scattered defines.
> +
> static const struct inode_operations btrfs_dir_inode_operations;
> static const struct inode_operations btrfs_symlink_inode_operations;
> static const struct inode_operations btrfs_dir_ro_inode_operations;
> @@ -6479,12 +6487,7 @@ static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
> u64 objectid;
> u64 index = 0;
>
> - /*
> - * 2 for inode item and ref
> - * 2 for dir items
> - * 1 for xattr if selinux is on
> - */
> - trans = btrfs_start_transaction(root, 5);
> + trans = btrfs_start_transaction(root, BTRFS_NEW_INODE_ITEMS);
> if (IS_ERR(trans))
> return PTR_ERR(trans);
>
> @@ -6543,12 +6546,7 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
> u64 objectid;
> u64 index = 0;
>
> - /*
> - * 2 for inode item and ref
> - * 2 for dir items
> - * 1 for xattr if selinux is on
> - */
> - trans = btrfs_start_transaction(root, 5);
> + trans = btrfs_start_transaction(root, BTRFS_NEW_INODE_ITEMS);
> if (IS_ERR(trans))
> return PTR_ERR(trans);
>
> @@ -6695,12 +6693,7 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
> u64 objectid = 0;
> u64 index = 0;
>
> - /*
> - * 2 items for inode and ref
> - * 2 items for dir items
> - * 1 for xattr if selinux is on
> - */
> - trans = btrfs_start_transaction(root, 5);
> + trans = btrfs_start_transaction(root, BTRFS_NEW_INODE_ITEMS);
> if (IS_ERR(trans))
> return PTR_ERR(trans);
>
> @@ -9428,14 +9421,11 @@ static int btrfs_rename_exchange(struct inode *old_dir,
> down_read(&fs_info->subvol_sem);
>
> /*
> - * We want to reserve the absolute worst case amount of items. So if
> - * both inodes are subvols and we need to unlink them then that would
> - * require 4 item modifications, but if they are both normal inodes it
> - * would require 5 item modifications, so we'll assume their normal
> - * inodes. So 5 * 2 is 10, plus 2 for the new links, so 12 total items
> - * should cover the worst case number of items we'll modify.
> + * The same math from btrfs_rename applies here, except we need an extra
> + * 2 items for the new links.
> */
> - trans = btrfs_start_transaction(root, 12);
> + trans = btrfs_start_transaction(root,
> + (BTRFS_NEW_INODE_ITEMS << 1) + 2);
> if (IS_ERR(trans)) {
> ret = PTR_ERR(trans);
> goto out_notrans;
> @@ -9768,19 +9758,19 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
> if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
> down_read(&fs_info->subvol_sem);
> /*
> - * We want to reserve the absolute worst case amount of items. So if
> - * both inodes are subvols and we need to unlink them then that would
> - * require 4 item modifications, but if they are both normal inodes it
> - * would require 5 item modifications, so we'll assume they are normal
> - * inodes. So 5 * 2 is 10, plus 1 for the new link, so 11 total items
> - * should cover the worst case number of items we'll modify.
> - * If our rename has the whiteout flag, we need more 5 units for the
> - * new inode (1 inode item, 1 inode ref, 2 dir items and 1 xattr item
> - * when selinux is enabled).
> + * We want to reserve the absolute worst case amount of items. Subvol
> + * inodes don't have an inode item to worry about and don't have a
> + * selinux attr, so we use the BTRFS_NEW_INODE_ITEMS counter for how
> + * much it costs per inode to modify. Worse case we'll have to mess
> + * with 2 inodes, so 2 x BTRFS_NEW_INODE_ITEMS, and then we need an
> + * extra reservation for the new link.
> + *
> + * If our rename has the whiteout flag we need a full new inode which
> + * means another set of BTRFS_NEW_INODE_ITEMS.
> */
> - trans_num_items = 11;
> + trans_num_items = (BTRFS_NEW_INODE_ITEMS << 1) + 1;
> if (flags & RENAME_WHITEOUT)
> - trans_num_items += 5;
> + trans_num_items += BTRFS_NEW_INODE_ITEMS;
> trans = btrfs_start_transaction(root, trans_num_items);
> if (IS_ERR(trans)) {
> ret = PTR_ERR(trans);
> @@ -10149,14 +10139,8 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
> if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info))
> return -ENAMETOOLONG;
>
> - /*
> - * 2 items for inode item and ref
> - * 2 items for dir items
> - * 1 item for updating parent inode item
> - * 1 item for the inline extent item
> - * 1 item for xattr if selinux is on
> - */
> - trans = btrfs_start_transaction(root, 7);
> + /* 1 item for the inline extent item */
> + trans = btrfs_start_transaction(root, BTRFS_NEW_INODE_ITEMS + 1);
> if (IS_ERR(trans))
> return PTR_ERR(trans);
>
> @@ -10427,10 +10411,8 @@ static int btrfs_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
> u64 index;
> int ret = 0;
>
> - /*
> - * 5 units required for adding orphan entry
> - */
> - trans = btrfs_start_transaction(root, 5);
> + /* 1 unit required for adding orphan entry */
> + trans = btrfs_start_transaction(root, BTRFS_NEW_INODE_ITEMS + 1);
> if (IS_ERR(trans))
> return PTR_ERR(trans);
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index f38a659c918c..21f8ab2d8570 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -83,6 +83,17 @@ struct btrfs_ioctl_send_args_32 {
> struct btrfs_ioctl_send_args_32)
> #endif
>
> +/*
> + * 1 - parent dir inode
> + * 2 - dir entries
> + * 1 - root item
> + * 2 - root ref/backref
> + * 1 - root of snapshot
> + * 1 - UUID item
> + * 1 - properties
> + */
> +#define BTRFS_NEW_ROOT_ITEMS 9
Even if you choose to have defines currently, I insist on them being
grouped in one place e.g. ctree.h
> +
> static int btrfs_clone(struct inode *src, struct inode *inode,
> u64 off, u64 olen, u64 olen_aligned, u64 destoff,
> int no_time_update);
> @@ -596,7 +607,8 @@ static noinline int create_subvol(struct inode *dir,
> * The same as the snapshot creation, please see the comment
> * of create_snapshot().
> */
> - ret = btrfs_subvolume_reserve_metadata(root, &block_rsv, 8, false);
> + ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
> + BTRFS_NEW_ROOT_ITEMS, false);
> if (ret)
> goto fail_free;
>
> @@ -804,17 +816,10 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
>
> btrfs_init_block_rsv(&pending_snapshot->block_rsv,
> BTRFS_BLOCK_RSV_TEMP);
> - /*
> - * 1 - parent dir inode
> - * 2 - dir entries
> - * 1 - root item
> - * 2 - root ref/backref
> - * 1 - root of snapshot
> - * 1 - UUID item
> - */
> +
> ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
> - &pending_snapshot->block_rsv, 8,
> - false);
> + &pending_snapshot->block_rsv,
> + BTRFS_NEW_ROOT_ITEMS, false);
> if (ret)
> goto dec_and_free;
>
>
