Commit 36f05cab authored by Jeff Layton's avatar Jeff Layton Committed by Andrew Morton

tmpfs: add support for an i_version counter

NFSv4 mandates a change attribute to avoid problems with timestamp
granularity, which Linux implements using the i_version counter. This is
particularly important when the underlying filesystem is fast.

Give tmpfs an i_version counter. Since it doesn't have to be persistent,
we can just turn on SB_I_VERSION and sprinkle some inode_inc_iversion
calls in the right places.

Also, while there is no formal spec for xattrs, most implementations
update the ctime on setxattr. Fix shmem_xattr_handler_set to update the
ctime and bump the i_version appropriately.

Link: https://lkml.kernel.org/r/20220909130031.15477-1-jlayton@kernel.orgSigned-off-by: default avatarJeff Layton <jlayton@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5934ec13
......@@ -24,6 +24,7 @@
#include <linux/user_namespace.h>
#include <linux/namei.h>
#include <linux/mnt_idmapping.h>
#include <linux/iversion.h>
static struct posix_acl **acl_by_type(struct inode *inode, int type)
{
......@@ -1073,6 +1074,8 @@ int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
}
inode->i_ctime = current_time(inode);
if (IS_I_VERSION(inode))
inode_inc_iversion(inode);
set_cached_acl(inode, type, acl);
return 0;
}
......
......@@ -38,6 +38,7 @@
#include <linux/hugetlb.h>
#include <linux/fs_parser.h>
#include <linux/swapfile.h>
#include <linux/iversion.h>
#include "swap.h"
static struct vfsmount *shm_mnt;
......@@ -1030,6 +1031,7 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
{
shmem_undo_range(inode, lstart, lend, false);
inode->i_ctime = inode->i_mtime = current_time(inode);
inode_inc_iversion(inode);
}
EXPORT_SYMBOL_GPL(shmem_truncate_range);
......@@ -1074,6 +1076,8 @@ static int shmem_setattr(struct user_namespace *mnt_userns,
struct inode *inode = d_inode(dentry);
struct shmem_inode_info *info = SHMEM_I(inode);
int error;
bool update_mtime = false;
bool update_ctime = true;
error = setattr_prepare(&init_user_ns, dentry, attr);
if (error)
......@@ -1094,7 +1098,9 @@ static int shmem_setattr(struct user_namespace *mnt_userns,
if (error)
return error;
i_size_write(inode, newsize);
inode->i_ctime = inode->i_mtime = current_time(inode);
update_mtime = true;
} else {
update_ctime = false;
}
if (newsize <= oldsize) {
loff_t holebegin = round_up(newsize, PAGE_SIZE);
......@@ -1114,6 +1120,12 @@ static int shmem_setattr(struct user_namespace *mnt_userns,
setattr_copy(&init_user_ns, inode, attr);
if (attr->ia_valid & ATTR_MODE)
error = posix_acl_chmod(&init_user_ns, inode, inode->i_mode);
if (!error && update_ctime) {
inode->i_ctime = current_time(inode);
if (update_mtime)
inode->i_mtime = inode->i_ctime;
inode_inc_iversion(inode);
}
return error;
}
......@@ -2890,6 +2902,7 @@ shmem_mknod(struct user_namespace *mnt_userns, struct inode *dir,
error = 0;
dir->i_size += BOGO_DIRENT_SIZE;
dir->i_ctime = dir->i_mtime = current_time(dir);
inode_inc_iversion(dir);
d_instantiate(dentry, inode);
dget(dentry); /* Extra count - pin the dentry in core */
}
......@@ -2965,6 +2978,7 @@ static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentr
dir->i_size += BOGO_DIRENT_SIZE;
inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
inode_inc_iversion(dir);
inc_nlink(inode);
ihold(inode); /* New dentry reference */
dget(dentry); /* Extra pinning count for the created dentry */
......@@ -2982,6 +2996,7 @@ static int shmem_unlink(struct inode *dir, struct dentry *dentry)
dir->i_size -= BOGO_DIRENT_SIZE;
inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
inode_inc_iversion(dir);
drop_nlink(inode);
dput(dentry); /* Undo the count from "create" - this does all the work */
return 0;
......@@ -3071,6 +3086,8 @@ static int shmem_rename2(struct user_namespace *mnt_userns,
old_dir->i_ctime = old_dir->i_mtime =
new_dir->i_ctime = new_dir->i_mtime =
inode->i_ctime = current_time(old_dir);
inode_inc_iversion(old_dir);
inode_inc_iversion(new_dir);
return 0;
}
......@@ -3123,6 +3140,7 @@ static int shmem_symlink(struct user_namespace *mnt_userns, struct inode *dir,
}
dir->i_size += BOGO_DIRENT_SIZE;
dir->i_ctime = dir->i_mtime = current_time(dir);
inode_inc_iversion(dir);
d_instantiate(dentry, inode);
dget(dentry);
return 0;
......@@ -3194,6 +3212,7 @@ static int shmem_fileattr_set(struct user_namespace *mnt_userns,
shmem_set_inode_flags(inode, info->fsflags);
inode->i_ctime = current_time(inode);
inode_inc_iversion(inode);
return 0;
}
......@@ -3257,9 +3276,15 @@ static int shmem_xattr_handler_set(const struct xattr_handler *handler,
size_t size, int flags)
{
struct shmem_inode_info *info = SHMEM_I(inode);
int err;
name = xattr_full_name(handler, name);
return simple_xattr_set(&info->xattrs, name, value, size, flags, NULL);
err = simple_xattr_set(&info->xattrs, name, value, size, flags, NULL);
if (!err) {
inode->i_ctime = current_time(inode);
inode_inc_iversion(inode);
}
return err;
}
static const struct xattr_handler shmem_security_xattr_handler = {
......@@ -3722,7 +3747,7 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
sb->s_flags |= SB_NOUSER;
}
sb->s_export_op = &shmem_export_ops;
sb->s_flags |= SB_NOSEC;
sb->s_flags |= SB_NOSEC | SB_I_VERSION;
#else
sb->s_flags |= SB_NOUSER;
#endif
......
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