This patch adds a new file ioctl to retrieve the parent
pointer of a given inode
Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
---
fs/xfs/libxfs/xfs_attr.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++
fs/xfs/libxfs/xfs_fs.h | 1 +
fs/xfs/xfs_attr.h | 2 ++
fs/xfs/xfs_attr_list.c | 3 +++
fs/xfs/xfs_ioctl.c | 48 +++++++++++++++++++++++++++++++++-
5 files changed, 120 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 9d4d883..d2be842 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -134,6 +134,73 @@ xfs_attr_get_ilocked(
return xfs_attr_node_get(args);
}
+/*
+ * Get the parent pointer for a given inode
+ * Caller will need to allocate a buffer pointed to by xpnir->p_name
+ * and store the buffer size in xpnir->p_namelen. The parent
+ * pointer will be stored in the given xfs_parent_name_irec
+ *
+ * Returns 0 on success and non zero on error
+ */
+int
+xfs_attr_get_parent_pointer(struct xfs_inode *ip,
+ struct xfs_parent_name_irec *xpnir)
+{
+ struct attrlist *alist;
+ struct attrlist_ent *aent;
+ struct attrlist_cursor_kern cursor;
+ struct xfs_parent_name_rec *xpnr;
+ char *namebuf;
+ int error = 0;
+ unsigned int flags = ATTR_PARENT;
+
+ /* Allocate a buffer to store the attribute names */
+ namebuf = kmem_zalloc_large(XFS_XATTR_LIST_MAX, KM_SLEEP);
+ if (!namebuf)
+ return -ENOMEM;
+
+ /* Get all attribute names that have the ATTR_PARENT flag */
+ memset(&cursor, 0, sizeof(struct attrlist_cursor_kern));
+ error = xfs_attr_list(ip, namebuf, XFS_XATTR_LIST_MAX, flags, &cursor);
+ if (error)
+ goto out_kfree;
+
+ alist = (struct attrlist *)namebuf;
+
+ /* There should never be more than one parent pointer */
+ ASSERT(alist->al_count == 1);
+
+ aent = (struct attrlist_ent *) &namebuf[alist->al_offset[0]];
+ xpnr = (struct xfs_parent_name_rec *)(aent->a_name);
+
+ /*
+ * The value of the parent pointer attribute should be the file name
+ * So we check the value length of the attribute entry against the name
+ * length of the parent name record to make sure the caller gave enough
+ * buffer space to store the file name (plus a null terminator)
+ */
+ if (aent->a_valuelen >= xpnir->p_namelen) {
+ error = -ERANGE;
+ goto out_kfree;
+ }
+
+ xpnir->p_namelen = aent->a_valuelen + 1;
+ memset((void *)(xpnir->p_name), 0, xpnir->p_namelen);
+ error = xfs_attr_get(ip, (char *)xpnr,
+ sizeof(struct xfs_parent_name_rec),
+ (unsigned char *)(xpnir->p_name),
+ (int *)&(xpnir->p_namelen), flags);
+ if (error)
+ goto out_kfree;
+
+ xfs_init_parent_name_irec(xpnir, xpnr);
+
+out_kfree:
+ kmem_free(namebuf);
+
+ return error;
+}
+
/* Retrieve an extended attribute by name, and its value. */
int
xfs_attr_get(
diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index b8108f8..2f9ca2c 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -512,6 +512,7 @@ typedef struct xfs_swapext
#define XFS_IOC_ZERO_RANGE _IOW ('X', 57, struct xfs_flock64)
#define XFS_IOC_FREE_EOFBLOCKS _IOR ('X', 58, struct xfs_fs_eofblocks)
/* XFS_IOC_GETFSMAP ------ hoisted 59 */
+#define XFS_IOC_GETPPOINTER _IOR ('X', 61, struct xfs_parent_name_irec)
/*
* ioctl commands that replace IRIX syssgi()'s
diff --git a/fs/xfs/xfs_attr.h b/fs/xfs/xfs_attr.h
index 0829687..0ec3458 100644
--- a/fs/xfs/xfs_attr.h
+++ b/fs/xfs/xfs_attr.h
@@ -172,6 +172,8 @@ int xfs_attr_get(struct xfs_inode *ip, const unsigned char *name,
int flags);
int xfs_attr_set(struct xfs_inode *dp, const unsigned char *name,
size_t namelen, unsigned char *value, int valuelen, int flags);
+int xfs_attr_get_parent_pointer(struct xfs_inode *ip,
+ struct xfs_parent_name_irec *xpnir);
int xfs_attr_set_args(struct xfs_da_args *args, int flags, bool roll_trans);
int xfs_attr_remove(struct xfs_inode *dp, const unsigned char *name,
size_t namelen, int flags);
diff --git a/fs/xfs/xfs_attr_list.c b/fs/xfs/xfs_attr_list.c
index 7740c8a..78fc477 100644
--- a/fs/xfs/xfs_attr_list.c
+++ b/fs/xfs/xfs_attr_list.c
@@ -534,6 +534,9 @@ xfs_attr_put_listent(
if (((context->flags & ATTR_ROOT) == 0) !=
((flags & XFS_ATTR_ROOT) == 0))
return;
+ if (((context->flags & ATTR_PARENT) == 0) !=
+ ((flags & XFS_ATTR_PARENT) == 0))
+ return;
arraytop = sizeof(*alist) +
context->count * sizeof(alist->al_offset[0]);
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 4664314..5492607 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -44,6 +44,7 @@
#include "xfs_btree.h"
#include <linux/fsmap.h>
#include "xfs_fsmap.h"
+#include "xfs_attr.h"
#include <linux/capability.h>
#include <linux/cred.h>
@@ -1710,6 +1711,50 @@ xfs_ioc_getfsmap(
return 0;
}
+/*
+ * IOCTL routine to get the parent pointer of an inode and return it to user
+ * space. Caller must pass an struct xfs_parent_name_irec with a name buffer
+ * large enough to hold the file name. Returns 0 on success or non-zero on
+ * failure
+ */
+STATIC int
+xfs_ioc_get_parent_pointer(
+ struct file *filp,
+ void __user *arg)
+{
+ struct inode *inode = file_inode(filp);
+ struct xfs_inode *ip = XFS_I(inode);
+ struct xfs_parent_name_irec xpnir;
+ char *uname;
+ char *kname;
+ int error = 0;
+
+ copy_from_user(&xpnir, arg, sizeof(struct xfs_parent_name_irec));
+ uname = (char *)xpnir.p_name;
+
+ /*
+ * Use kernel space memory to get the parent pointer name.
+ * We'll copy it to the user space name back when we're done
+ */
+ kname = kmem_zalloc_large(xpnir.p_namelen, KM_SLEEP);
+ if (!kname)
+ return -ENOMEM;
+
+ xpnir.p_name = kname;
+ error = xfs_attr_get_parent_pointer(ip, &xpnir);
+
+ if (error)
+ goto out;
+
+ copy_to_user(uname, xpnir.p_name, xpnir.p_namelen);
+ xpnir.p_name = uname;
+ copy_to_user(arg, &xpnir, sizeof(struct xfs_parent_name_irec));
+
+out:
+ kmem_free(kname);
+ return error;
+}
+
int
xfs_ioc_swapext(
xfs_swapext_t *sxp)
@@ -1866,7 +1911,8 @@ xfs_file_ioctl(
return xfs_ioc_getxflags(ip, arg);
case XFS_IOC_SETXFLAGS:
return xfs_ioc_setxflags(ip, filp, arg);
-
+ case XFS_IOC_GETPPOINTER:
+ return xfs_ioc_get_parent_pointer(filp, arg);
case XFS_IOC_FSSETDM: {
struct fsdmidata dmi;
--
2.7.4
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