sysfs, kernfs: add sysfs_dirent->s_attr.size

sysfs sets the size of regular files unconditionally at PAGE_SIZE and
takes the size of bin files from bin_attribute.  The latter is a
pretty bad interface which forces bin_attribute users to create a
separate copy of bin_attribute for each instance of the file -
e.g. pci resource files.

Add sysfs_dirent->s_attr.size so that the size can be specified
separately.  This unifies inode init paths of ATTR and BIN_ATTR
identical and allows for generic size handling for kernfs.

Unfortunately, this grows the size of sysfs_dirent by sizeof(loff_t).

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index cbebc335af8c..0b0cec8e9d8f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -923,6 +923,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
         const struct kernfs_ops *ops;
         struct sysfs_addrm_cxt acxt;
         struct sysfs_dirent *sd;
+        loff_t size;
         int rc;
 
         if (type == SYSFS_KOBJ_ATTR) {
@@ -943,6 +944,8 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
                         ops = &sysfs_file_kfops_wo;
                 else
                         ops = &sysfs_file_kfops_empty;
+
+                size = PAGE_SIZE;
         } else {
                 struct bin_attribute *battr = (void *)attr;
 
@@ -954,6 +957,8 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
                         ops = &sysfs_bin_kfops_wo;
                 else
                         ops = &sysfs_file_kfops_empty;
+
+                size = battr->size;
         }
 
         sd = sysfs_new_dirent(attr->name, mode, type);
@@ -961,6 +966,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
                 return -ENOMEM;
 
         sd->s_attr.ops = ops;
+        sd->s_attr.size = size;
         sd->s_ns = ns;
         sd->priv = (void *)attr;
         sysfs_dirent_init_lockdep(sd);