On Wed, Oct 18, 2017 at 03:55:19PM -0700, Allison Henderson wrote:
> These routines set up set and start a new deferred attribute
> operation. These functions are meant to be called by other
> code needing to initiate a deferred attribute operation. We
> will use these routines later in the parent pointer patches.
>
> Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_attr.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++
> fs/xfs/xfs_attr.h | 7 ++++++
> 2 files changed, 65 insertions(+)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 5325ec2..59f3502 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -458,6 +458,37 @@ xfs_attr_set(
> return error;
> }
>
> +int
> +xfs_attr_set_deferred(
> + struct xfs_inode *dp,
> + struct xfs_defer_ops *dfops,
> + const unsigned char *name,
> + unsigned int namelen,
> + unsigned char *value,
> + unsigned int valuelen,
> + int flags)
> +{
> +
> + struct xfs_attr_item *new;
> +
> + ASSERT(namelen != 0);
> + ASSERT(valuelen != 0);
> +
> + new = kmem_alloc(sizeof(struct xfs_attr_item), KM_SLEEP|KM_NOFS);
Yikes, this is a 66,000 byte allocation. I wouldn't take it for granted
that we can ask for more than a page's worth of memory.
Seeing as we already know namelen and valuelen, let's go for the
zero length array at the end of the struct approach:
struct xfs_attr_item {
...
uint16_t xattri_namelen;
uint8_t xattri_namevalue[0];
};
#define XFS_ATTR_ITEM_SIZEOF(namelen, valuelen) \
(sizeof(struct xfs_attr_item) + (namelen) + (valuelen))
new = kmem_alloc(XFS_ATTR_ITEM_SIZEOF(namelen, valuelen), KM...);
if (!new)
return -ENOMEM;
memcpy(new->xattri_namevalue, name, namelen);
new->xattri_namelen = namelen;
memcpy(&new->xattri_namevalue[namelen], value, valuelen);
...
Assuming there isn't a way to attach the caller's buffers to the attr
item without copying anything(?) (It would be nice if we could, but
between the defer_add and the defer_finish a lot can happen w.r.t.
variable scope so that might be a bad idea.)
> + memset(new, 0, sizeof(struct xfs_attr_item));
> + new->xattri_ino = dp->i_ino;
> + new->xattri_op_flags = ATTR_OP_FLAGS_SET;
> + new->xattri_name_len = namelen;
> + new->xattri_value_len = valuelen;
> + new->xattri_flags = flags;
> + memcpy(new->xattri_name, name, namelen);
> + memcpy(&new->xattri_value, value, valuelen);
> +
> + xfs_defer_add(dfops, XFS_DEFER_OPS_TYPE_ATTR, &new->xattri_list);
> +
> + return 0;
> +}
> +
> /*
> * Generic handler routine to remove a name from an attribute list.
> * Transitions attribute list from Btree to shortform as necessary.
> @@ -531,6 +562,33 @@ xfs_attr_remove(
> return error;
> }
>
> +int
> +xfs_attr_remove_deferred(
> + struct xfs_inode *dp,
> + struct xfs_defer_ops *dfops,
> + const unsigned char *name,
> + unsigned int namelen,
> + int flags)
> +{
> +
> + struct xfs_attr_item *new;
> +
> + ASSERT(namelen != 0);
> +
> + new = kmem_alloc(sizeof(struct xfs_attr_item), KM_SLEEP|KM_NOFS);
> + memset(new, 0, sizeof(struct xfs_attr_item));
> + new->xattri_ino = dp->i_ino;
> + new->xattri_op_flags = ATTR_OP_FLAGS_REMOVE;
> + new->xattri_name_len = namelen;
> + new->xattri_value_len = 0;
> + new->xattri_flags = flags;
> + memcpy(new->xattri_name, name, namelen);
> +
> + xfs_defer_add(dfops, XFS_DEFER_OPS_TYPE_ATTR, &new->xattri_list);
> +
> + return 0;
> +}
> +
> /*========================================================================
> * External routines when attribute list is inside the inode
> *========================================================================*/
> diff --git a/fs/xfs/xfs_attr.h b/fs/xfs/xfs_attr.h
> index 34bb4cb..f4a53fd 100644
> --- a/fs/xfs/xfs_attr.h
> +++ b/fs/xfs/xfs_attr.h
> @@ -173,5 +173,12 @@ int xfs_attr_list(struct xfs_inode *dp, char *buffer, int bufsize,
> int xfs_attr_args_init(struct xfs_da_args *args, struct xfs_inode *dp,
> const unsigned char *name, int flags);
> int xfs_attr_calc_size(struct xfs_da_args *args, int *local);
> +int xfs_attr_set_deferred(struct xfs_inode *dp, struct xfs_defer_ops *dfops,
> + const unsigned char *name, unsigned int name_len,
> + unsigned char *value, unsigned int valuelen,
> + int flags);
> +int xfs_attr_remove_deferred(struct xfs_inode *dp, struct xfs_defer_ops *dfops,
> + const unsigned char *name, unsigned int namelen,
> + int flags);
>
> #endif /* __XFS_ATTR_H__ */
> --
> 2.7.4
>
> --
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