On Oct 22, 2019, at 2:44 PM, Mark Salyzyn <salyzyn@xxxxxxxxxxx> wrote:
>
> Replace arguments for get and set xattr methods, and __vfs_getxattr
> and __vfs_setaxtr functions with a reference to the following now
> common argument structure:
>
> struct xattr_gs_args {
> struct dentry *dentry;
> struct inode *inode;
> const char *name;
> union {
> void *buffer;
> const void *value;
> };
> size_t size;
> int flags;
> };
As part of this change (which is touching all of the uses of these
fields anyway) it would be useful to give these structure fields a
prefix like "xga_" so that they can be easily found with tags.
Otherwise, there are so many different "dentry" and "inode" fields
in various structures that it is hard to find the right one.
> #define __USE_KERNEL_XATTR_DEFS
>
> -#define XATTR_CREATE 0x1 /* set value, fail if attr already exists */
> -#define XATTR_REPLACE 0x2 /* set value, fail if attr does not exist */
> +#define XATTR_CREATE 0x1 /* set value, fail if attr already exists */
> +#define XATTR_REPLACE 0x2 /* set value, fail if attr does not exist */
> +#ifdef __KERNEL__ /* following is kernel internal, colocated for maintenance */
> +#define XATTR_NOSECURITY 0x4 /* get value, do not involve security check */
> +#endif
Now that these arguments are separated out into their own structure,
rather than using "int flags" (there are a million different flags in
the kernel and easily confused) it would be immediately clear *which*
flags are used here with a named enum, like:
enum xattr_flags {
XATTR_CREATE = 0x1, /* set value, fail if attr already exists */
XATTR_REPLACE = 0x2, /* set value, fail if attr does not exist */
#ifdef __KERNEL__ /* following is kernel internal, colocated for maintenance */
XATTR_NOSECURITY= 0x4, /* get value, do not involve security check */
#endif
};
and use this in the struct like:
struct xattr_gs_args {
struct dentry *xga_dentry;
struct inode *xga_inode;
const char *xga_name;
union {
void *xga_buffer;
const void *xga_value;
};
size_t xga_size;
enum xattr_flags xga_flags;
};
Beyond the benefit for the reader to understand the code better, this
can also allow the compiler to warn if incorrect values are being
assigned to this field.
Cheers, Andreas
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