* [PATCHv1 1/2] libfs: allow simple_fill_super() to add symlinks
2016-05-16 17:44 [PATCHv1 0/2] xen/xenfs: fix /proc/xen/xenbus David Vrabel
@ 2016-05-16 17:44 ` David Vrabel
2016-05-16 17:44 ` [PATCHv1 2/2] xen/xenfs: replace xenbus and privcmd with symlinks David Vrabel
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: David Vrabel @ 2016-05-16 17:44 UTC (permalink / raw)
To: xen-devel; +Cc: Juergen Gross, Boris Ostrovsky, David Vrabel
simple_fill_super() will add symlinks if an entry has mode & S_IFLNK.
The target is provided in the new "link" field.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
fs/libfs.c | 23 ++++++++++++++++++++---
include/linux/fs.h | 2 +-
2 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/fs/libfs.c b/fs/libfs.c
index f3fa82c..894e182 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -500,6 +500,8 @@ int simple_fill_super(struct super_block *s, unsigned long magic,
if (!root)
return -ENOMEM;
for (i = 0; !files->name || files->name[0]; i++, files++) {
+ char *link = NULL;
+
if (!files->name)
continue;
@@ -509,17 +511,32 @@ int simple_fill_super(struct super_block *s, unsigned long magic,
"with an index of 1!\n", __func__,
s->s_type->name);
+ if (files->mode & S_IFLNK) {
+ link = kstrdup(files->link, GFP_KERNEL);
+ if (!link)
+ goto out;
+ }
+
dentry = d_alloc_name(root, files->name);
- if (!dentry)
+ if (!dentry) {
+ kfree(link);
goto out;
+ }
inode = new_inode(s);
if (!inode) {
dput(dentry);
+ kfree(link);
goto out;
}
- inode->i_mode = S_IFREG | files->mode;
+ inode->i_mode = files->mode;
+ if (files->mode & S_IFLNK) {
+ inode->i_op = &simple_symlink_inode_operations;
+ inode->i_link = link;
+ } else {
+ inode->i_fop = files->ops;
+ inode->i_mode |= S_IFREG;
+ }
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
- inode->i_fop = files->ops;
inode->i_ino = i;
d_add(dentry, inode);
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 70e61b5..8a09998 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2897,7 +2897,7 @@ extern const struct file_operations simple_dir_operations;
extern const struct inode_operations simple_dir_inode_operations;
extern void make_empty_dir_inode(struct inode *inode);
extern bool is_empty_dir_inode(struct inode *inode);
-struct tree_descr { char *name; const struct file_operations *ops; int mode; };
+struct tree_descr { char *name; const struct file_operations *ops; int mode; char *link; };
struct dentry *d_alloc_name(struct dentry *, const char *);
extern int simple_fill_super(struct super_block *, unsigned long, struct tree_descr *);
extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
--
2.1.4
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^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCHv1 2/2] xen/xenfs: replace xenbus and privcmd with symlinks
2016-05-16 17:44 [PATCHv1 0/2] xen/xenfs: fix /proc/xen/xenbus David Vrabel
2016-05-16 17:44 ` [PATCHv1 1/2] libfs: allow simple_fill_super() to add symlinks David Vrabel
@ 2016-05-16 17:44 ` David Vrabel
2016-05-16 18:36 ` [PATCHv1 0/2] xen/xenfs: fix /proc/xen/xenbus Boris Ostrovsky
2016-05-16 22:23 ` Doug Goldstein
3 siblings, 0 replies; 5+ messages in thread
From: David Vrabel @ 2016-05-16 17:44 UTC (permalink / raw)
To: xen-devel; +Cc: Juergen Gross, Boris Ostrovsky, David Vrabel
/proc/xen/xenbus does not work correctly. A read blocked waiting for
a xenbus message will deadlock a write to the same file handle due to
the requirement for atomic file position updates on regular files.
/proc/xen/xenbus and /proc/xen/privcmd are supposed to be identical to
the character devices /dev/xen/xenbus and /dev/xen/privcmd so replace
the files with symlinks.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
drivers/xen/xenfs/super.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/xen/xenfs/super.c b/drivers/xen/xenfs/super.c
index 8559a71..09c239e 100644
--- a/drivers/xen/xenfs/super.c
+++ b/drivers/xen/xenfs/super.c
@@ -45,16 +45,16 @@ static const struct file_operations capabilities_file_ops = {
static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
{
static struct tree_descr xenfs_files[] = {
- [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
+ [2] = { "xenbus", NULL, S_IFLNK | S_IRWXUGO, "/dev/xen/xenbus" },
{ "capabilities", &capabilities_file_ops, S_IRUGO },
- { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
+ { "privcmd", NULL, S_IFLNK | S_IRWXUGO, "/dev/xen/privcmd" },
{""},
};
static struct tree_descr xenfs_init_files[] = {
- [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
+ [2] = { "xenbus", NULL, S_IFLNK | S_IRWXUGO, "/dev/xen/xenbus" },
{ "capabilities", &capabilities_file_ops, S_IRUGO },
- { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
+ { "privcmd", NULL, S_IFLNK | S_IRWXUGO, "/dev/xen/privcmd" },
{ "xsd_kva", &xsd_kva_file_ops, S_IRUSR|S_IWUSR},
{ "xsd_port", &xsd_port_file_ops, S_IRUSR|S_IWUSR},
#ifdef CONFIG_XEN_SYMS
--
2.1.4
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^ permalink raw reply related [flat|nested] 5+ messages in thread