The GET ioctl is trivial, just return the current label.
The SET ioctl is more involved:
It transactionally modifies the superblock to write a new filesystem
label to the primary super.
It then also checkpoints the log to disk so that the change lands in
block 0, invalidates any page cache that userspace might have previously
read, and updates all secondary superblocks as userspace relable does.
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
nb: the growfs trylock is just cargo-culting; growfs also trylocks. *shrug*
fs/xfs/xfs_ioctl.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 83 insertions(+)
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 89fb1eb..12c6711 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -20,6 +20,7 @@
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
+#include "xfs_log.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
@@ -1811,6 +1812,84 @@ struct getfsmap_info {
return error;
}
+static int
+xfs_ioc_getlabel(
+ struct xfs_mount *mp,
+ char __user *label)
+{
+ struct xfs_sb *sbp = &mp->m_sb;
+
+ /* Paranoia */
+ BUILD_BUG_ON(sizeof(sbp->sb_fname) > FSLABEL_MAX);
+
+ if (copy_to_user(label, sbp->sb_fname, sizeof(sbp->sb_fname)))
+ return -EFAULT;
+ return 0;
+}
+
+static int
+xfs_ioc_setlabel(
+ struct file *filp,
+ struct xfs_mount *mp,
+ char __user *newlabel)
+{
+ struct address_space *mapping;
+ struct xfs_sb *sbp = &mp->m_sb;
+ char label[FSLABEL_MAX];
+ size_t len;
+ int error;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (copy_from_user(label, newlabel, FSLABEL_MAX))
+ return -EFAULT;
+ /*
+ * The generic ioctl allows up to FSLABEL_MAX chars, but xfs is much
+ * smaller, at 12 bytes.
+ * NB: The on disk label doesn't need to be null terminated.
+ */
+ len = strnlen(label, FSLABEL_MAX);
+ if (len > sizeof(sbp->sb_fname)) {
+ xfs_warn(mp, "label %s is too long, max %zu chars",
+ label, sizeof(sbp->sb_fname));
+ return -EINVAL;
+ }
+
+ error = mnt_want_write_file(filp);
+ if (error)
+ return error;
+
+ spin_lock(&mp->m_sb_lock);
+ memset(sbp->sb_fname, 0, sizeof(sbp->sb_fname));
+ strncpy(sbp->sb_fname, label, sizeof(sbp->sb_fname));
+ spin_unlock(&mp->m_sb_lock);
+
+ error = xfs_sync_sb(mp, true);
+ if (error)
+ goto out;
+
+ /* checkpoint the log to update primary super in fs itself */
+ error = xfs_log_checkpoint(mp);
+ if (error)
+ goto out;
+
+ /* invalidate any cached bdev page for userspace visibility */
+ mapping = mp->m_ddev_targp->bt_bdev->bd_inode->i_mapping;
+ error = invalidate_inode_pages2_range(mapping, 0, 0);
+ if (error)
+ goto out;
+
+ /* update the backup superblocks like userspace does */
+ if (mutex_trylock(&mp->m_growlock)) {
+ error = xfs_update_secondary_supers(mp, mp->m_sb.sb_agcount, 0);
+ mutex_unlock(&mp->m_growlock);
+ }
+out:
+ mnt_drop_write_file(filp);
+ return error;
+}
+
/*
* Note: some of the ioctl's return positive numbers as a
* byte count indicating success, such as readlink_by_handle.
@@ -1834,6 +1913,10 @@ struct getfsmap_info {
switch (cmd) {
case FITRIM:
return xfs_ioc_trim(mp, arg);
+ case FS_IOC_GET_FSLABEL:
+ return xfs_ioc_getlabel(mp, arg);
+ case FS_IOC_SET_FSLABEL:
+ return xfs_ioc_setlabel(filp, mp, arg);
case XFS_IOC_ALLOCSP:
case XFS_IOC_FREESP:
case XFS_IOC_RESVSP:
--
1.8.3.1
--
To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
