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Linux 4.5 compat: get_link() / put_link()

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The follow_link() interface was retired in favor of get_link().
In the process of phasing in get_link() the Linux kernel went
through two different versions.  The first of which depended
on put_link() and the final version on a delayed done function.

- Improved configure checks for .follow_link, .get_link, .put_link.
  - Interfaces checked from newest to oldest.
  - Strict checking for each possible known interface.
  - Configure fails when no known interface is available.

- Both versions .get_link are detected and supported as well
  two previous versions of .follow_link.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Issue #4228
This commit is contained in:
Brian Behlendorf
2016-01-14 13:25:10 -05:00
parent bc89ac8479
commit beeed4596b
6 changed files with 259 additions and 87 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/zfs/zpl_inode.c
+98 -39
View File
@@ -367,26 +367,42 @@ zpl_symlink(struct inode *dir, struct dentry *dentry, const char *name)
return (error);
}
#ifdef HAVE_FOLLOW_LINK_NAMEIDATA
static void *
zpl_follow_link(struct dentry *dentry, struct nameidata *nd)
#else
const char *
zpl_follow_link(struct dentry *dentry, void **symlink_cookie)
#endif
#if defined(HAVE_PUT_LINK_COOKIE)
static void
zpl_put_link(struct inode *unused, void *cookie)
{
kmem_free(cookie, MAXPATHLEN);
}
#elif defined(HAVE_PUT_LINK_NAMEIDATA)
static void
zpl_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
{
const char *link = nd_get_link(nd);
if (!IS_ERR(link))
kmem_free(link, MAXPATHLEN);
}
#elif defined(HAVE_PUT_LINK_DELAYED)
static void
zpl_put_link(void *ptr)
{
kmem_free(ptr, MAXPATHLEN);
}
#endif
static int
zpl_get_link_common(struct dentry *dentry, struct inode *ip, char **link)
{
fstrans_cookie_t cookie;
cred_t *cr = CRED();
struct inode *ip = dentry->d_inode;
struct iovec iov;
uio_t uio;
char *link;
int error;
fstrans_cookie_t cookie;
crhold(cr);
*link = NULL;
iov.iov_len = MAXPATHLEN;
iov.iov_base = link = kmem_zalloc(MAXPATHLEN, KM_SLEEP);
iov.iov_base = kmem_zalloc(MAXPATHLEN, KM_SLEEP);
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
@@ -397,41 +413,78 @@ zpl_follow_link(struct dentry *dentry, void **symlink_cookie)
cookie = spl_fstrans_mark();
error = -zfs_readlink(ip, &uio, cr);
spl_fstrans_unmark(cookie);
if (error)
kmem_free(link, MAXPATHLEN);
crfree(cr);
#ifdef HAVE_FOLLOW_LINK_NAMEIDATA
if (error)
kmem_free(iov.iov_base, MAXPATHLEN);
else
*link = iov.iov_base;
return (error);
}
#if defined(HAVE_GET_LINK_DELAYED)
const char *
zpl_get_link(struct dentry *dentry, struct inode *inode,
struct delayed_call *done)
{
char *link = NULL;
int error;
if (!dentry)
return (ERR_PTR(-ECHILD));
error = zpl_get_link_common(dentry, inode, &link);
if (error)
return (ERR_PTR(error));
set_delayed_call(done, zpl_put_link, link);
return (link);
}
#elif defined(HAVE_GET_LINK_COOKIE)
const char *
zpl_get_link(struct dentry *dentry, struct inode *inode, void **cookie)
{
char *link = NULL;
int error;
if (!dentry)
return (ERR_PTR(-ECHILD));
error = zpl_get_link_common(dentry, inode, &link);
if (error)
return (ERR_PTR(error));
return (*cookie = link);
}
#elif defined(HAVE_FOLLOW_LINK_COOKIE)
const char *
zpl_follow_link(struct dentry *dentry, void **cookie)
{
char *link = NULL;
int error;
error = zpl_get_link_common(dentry, dentry->d_inode, &link);
if (error)
return (ERR_PTR(error));
return (*cookie = link);
}
#elif defined(HAVE_FOLLOW_LINK_NAMEIDATA)
static void *
zpl_follow_link(struct dentry *dentry, struct nameidata *nd)
{
char *link = NULL;
int error;
error = zpl_get_link_common(dentry, dentry->d_inode, &link);
if (error)
nd_set_link(nd, ERR_PTR(error));
else
nd_set_link(nd, link);
return (NULL);
#else
if (error)
return (ERR_PTR(error));
else
return (*symlink_cookie = link);
#endif
}
#ifdef HAVE_PUT_LINK_NAMEIDATA
static void
zpl_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
{
const char *link = nd_get_link(nd);
if (!IS_ERR(link))
kmem_free(link, MAXPATHLEN);
}
#else
static void
zpl_put_link(struct inode *unused, void *symlink_cookie)
{
kmem_free(symlink_cookie, MAXPATHLEN);
}
#endif
@@ -619,8 +672,14 @@ const struct inode_operations zpl_dir_inode_operations = {
const struct inode_operations zpl_symlink_inode_operations = {
.readlink = generic_readlink,
#if defined(HAVE_GET_LINK_DELAYED) || defined(HAVE_GET_LINK_COOKIE)
.get_link = zpl_get_link,
#elif defined(HAVE_FOLLOW_LINK_COOKIE) || defined(HAVE_FOLLOW_LINK_NAMEIDATA)
.follow_link = zpl_follow_link,
#endif
#if defined(HAVE_PUT_LINK_COOKIE) || defined(HAVE_PUT_LINK_NAMEIDATA)
.put_link = zpl_put_link,
#endif
.setattr = zpl_setattr,
.getattr = zpl_getattr,
.setxattr = generic_setxattr,