On Mon, Apr 01, 2024 at 11:26:54AM +0300, Dmitry Bogdanov wrote:
> Instead of preallocating PAGE_SIZE for a symlink path, allocate the exact
> size of that path.
>
> Fixes: e9c03af21cc7 (configfs: calculate the symlink target only once)
> Signed-off-by: Dmitry Bogdanov <d.bogdanov@xxxxxxxxx>
Reviewed-by: Joel Becker <jlbec@xxxxxxxxxxxx>
>
> ---
> I treat this as bugfux due to reducing of enourmous memory consumption.
> ---
> fs/configfs/symlink.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c
> index 0623c3edcfb9..224c9e4899d4 100644
> --- a/fs/configfs/symlink.c
> +++ b/fs/configfs/symlink.c
> @@ -54,7 +54,7 @@ static void fill_item_path(struct config_item * item, char * buffer, int length)
> }
>
> static int configfs_get_target_path(struct config_item *item,
> - struct config_item *target, char *path)
> + struct config_item *target, char **path)
> {
> int depth, size;
> char *s;
> @@ -66,11 +66,16 @@ static int configfs_get_target_path(struct config_item *item,
>
> pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size);
>
> - for (s = path; depth--; s += 3)
> + *path = kzalloc(size, GFP_KERNEL);
> + if (!*path)
> + return -ENOMEM;
> +
> +
> + for (s = *path; depth--; s += 3)
> strcpy(s,"../");
>
> - fill_item_path(target, path, size);
> - pr_debug("%s: path = '%s'\n", __func__, path);
> + fill_item_path(target, *path, size);
> + pr_debug("%s: path = '%s'\n", __func__, *path);
> return 0;
> }
>
> @@ -79,27 +84,22 @@ static int create_link(struct config_item *parent_item,
> struct dentry *dentry)
> {
> struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata;
> - char *body;
> + char *body = NULL;
> int ret;
>
> if (!configfs_dirent_is_ready(target_sd))
> return -ENOENT;
>
> - body = kzalloc(PAGE_SIZE, GFP_KERNEL);
> - if (!body)
> - return -ENOMEM;
> -
> configfs_get(target_sd);
> spin_lock(&configfs_dirent_lock);
> if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
> spin_unlock(&configfs_dirent_lock);
> configfs_put(target_sd);
> - kfree(body);
> return -ENOENT;
> }
> target_sd->s_links++;
> spin_unlock(&configfs_dirent_lock);
> - ret = configfs_get_target_path(parent_item, item, body);
> + ret = configfs_get_target_path(parent_item, item, &body);
> if (!ret)
> ret = configfs_create_link(target_sd, parent_item->ci_dentry,
> dentry, body);
> --
> 2.25.1
>
--
"Can any of you seriously say the Bill of Rights could get through
Congress today? It wouldn't even get out of committee."
- F. Lee Bailey
http://www.jlbec.org/
jlbec@xxxxxxxxxxxx
