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kernfs: Add removed_size out param for simple_xattr_set 

This helps set up size accounting in the next commit. Without this out
param, it's difficult to find out the removed xattr size without taking
a lock for longer and walking the xattr linked list twice.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Acked-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Daniel Xu 2020-03-12 13:03:15 -07:00 committed by Tejun Heo
parent fdc85222d5
commit a46a22955b
4 changed files with 14 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/kernfs/inode.c
View File

@ -303,7 +303,7 @@ int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
if (!attrs)
return -ENOMEM;
return simple_xattr_set(&attrs->xattrs, name, value, size, flags);
return simple_xattr_set(&attrs->xattrs, name, value, size, flags, NULL);
}
static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,

11
fs/xattr.c
View File

@ -860,6 +860,7 @@ int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
* @value: value of the xattr. If %NULL, will remove the attribute.
* @size: size of the new xattr
* @flags: %XATTR_{CREATE|REPLACE}
* @removed_size: returns size of the removed xattr, -1 if none removed
*
* %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
* with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist;
@ -868,7 +869,8 @@ int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
* Returns 0 on success, -errno on failure.
*/
int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
const void *value, size_t size, int flags)
const void *value, size_t size, int flags,
ssize_t *removed_size)
{
struct simple_xattr *xattr;
struct simple_xattr *new_xattr = NULL;
@ -895,8 +897,12 @@ int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
err = -EEXIST;
} else if (new_xattr) {
list_replace(&xattr->list, &new_xattr->list);
if (removed_size)
*removed_size = xattr->size;
} else {
list_del(&xattr->list);
if (removed_size)
*removed_size = xattr->size;
}
goto out;
}
@ -908,6 +914,9 @@ int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
list_add(&new_xattr->list, &xattrs->head);
xattr = NULL;
}
if (removed_size)
*removed_size = -1;
out:
spin_unlock(&xattrs->lock);
if (xattr) {

3
include/linux/xattr.h
View File

@ -102,7 +102,8 @@ struct simple_xattr *simple_xattr_alloc(const void *value, size_t size);
int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
void *buffer, size_t size);
int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
const void *value, size_t size, int flags);
const void *value, size_t size, int flags,
ssize_t *removed_size);
ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, char *buffer,
size_t size);
void simple_xattr_list_add(struct simple_xattrs *xattrs,

2
mm/shmem.c
View File

@ -3243,7 +3243,7 @@ static int shmem_xattr_handler_set(const struct xattr_handler *handler,
struct shmem_inode_info *info = SHMEM_I(inode);
name = xattr_full_name(handler, name);
return simple_xattr_set(&info->xattrs, name, value, size, flags);
return simple_xattr_set(&info->xattrs, name, value, size, flags, NULL);
}
static const struct xattr_handler shmem_security_xattr_handler = {