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linux-sg2042/fs/overlayfs/copy_up.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
*
* Copyright (C) 2011 Novell Inc.
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/splice.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include <linux/uaccess.h>
#include <linux/sched/signal.h>
#include <linux/cred.h>
#include <linux/namei.h>
#include <linux/fdtable.h>
#include <linux/ratelimit.h>
#include <linux/exportfs.h>
#include "overlayfs.h"
#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
static int ovl_ccup_set(const char *buf, const struct kernel_param *param)
{
pr_warn("\"check_copy_up\" module option is obsolete\n");
return 0;
}
static int ovl_ccup_get(char *buf, const struct kernel_param *param)
{
return sprintf(buf, "N\n");
}
module_param_call(check_copy_up, ovl_ccup_set, ovl_ccup_get, NULL, 0644);
MODULE_PARM_DESC(check_copy_up, "Obsolete; does nothing");
static bool ovl_must_copy_xattr(const char *name)
{
return !strcmp(name, XATTR_POSIX_ACL_ACCESS) ||
!strcmp(name, XATTR_POSIX_ACL_DEFAULT) ||
!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN);
}
int ovl_copy_xattr(struct super_block *sb, struct dentry *old,
struct dentry *new)
{
ssize_t list_size, size, value_size = 0;
char *buf, *name, *value = NULL;
int error = 0;
size_t slen;
if (!(old->d_inode->i_opflags & IOP_XATTR) ||
!(new->d_inode->i_opflags & IOP_XATTR))
return 0;
list_size = vfs_listxattr(old, NULL, 0);
if (list_size <= 0) {
if (list_size == -EOPNOTSUPP)
return 0;
return list_size;
}
buf = kzalloc(list_size, GFP_KERNEL);
if (!buf)
return -ENOMEM;
list_size = vfs_listxattr(old, buf, list_size);
if (list_size <= 0) {
error = list_size;
goto out;
}
for (name = buf; list_size; name += slen) {
slen = strnlen(name, list_size) + 1;
/* underlying fs providing us with an broken xattr list? */
if (WARN_ON(slen > list_size)) {
error = -EIO;
break;
}
list_size -= slen;
if (ovl_is_private_xattr(sb, name))
continue;
error = security_inode_copy_up_xattr(name);
if (error < 0 && error != -EOPNOTSUPP)
break;
if (error == 1) {
error = 0;
continue; /* Discard */
}
retry:
size = vfs_getxattr(&init_user_ns, old, name, value, value_size);
if (size == -ERANGE)
size = vfs_getxattr(&init_user_ns, old, name, NULL, 0);
if (size < 0) {
error = size;
break;
}
if (size > value_size) {
void *new;
new = krealloc(value, size, GFP_KERNEL);
if (!new) {
error = -ENOMEM;
break;
}
value = new;
value_size = size;
goto retry;
}
error = vfs_setxattr(&init_user_ns, new, name, value, size, 0);
if (error) {
if (error != -EOPNOTSUPP || ovl_must_copy_xattr(name))
break;
/* Ignore failure to copy unknown xattrs */
error = 0;
}
}
kfree(value);
out:
kfree(buf);
return error;
}
static int ovl_copy_up_data(struct ovl_fs *ofs, struct path *old,
struct path *new, loff_t len)
{
struct file *old_file;
struct file *new_file;
loff_t old_pos = 0;
loff_t new_pos = 0;
loff_t cloned;
loff_t data_pos = -1;
loff_t hole_len;
bool skip_hole = false;
int error = 0;
if (len == 0)
return 0;
old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY);
if (IS_ERR(old_file))
return PTR_ERR(old_file);
new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
if (IS_ERR(new_file)) {
error = PTR_ERR(new_file);
goto out_fput;
}
/* Try to use clone_file_range to clone up within the same fs */
cloned = do_clone_file_range(old_file, 0, new_file, 0, len, 0);
if (cloned == len)
goto out;
/* Couldn't clone, so now we try to copy the data */
/* Check if lower fs supports seek operation */
if (old_file->f_mode & FMODE_LSEEK &&
old_file->f_op->llseek)
skip_hole = true;
while (len) {
size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
long bytes;
if (len < this_len)
this_len = len;
if (signal_pending_state(TASK_KILLABLE, current)) {
error = -EINTR;
break;
}
/*
* Fill zero for hole will cost unnecessary disk space
* and meanwhile slow down the copy-up speed, so we do
* an optimization for hole during copy-up, it relies
* on SEEK_DATA implementation in lower fs so if lower
* fs does not support it, copy-up will behave as before.
*
* Detail logic of hole detection as below:
* When we detect next data position is larger than current
* position we will skip that hole, otherwise we copy
* data in the size of OVL_COPY_UP_CHUNK_SIZE. Actually,
* it may not recognize all kind of holes and sometimes
* only skips partial of hole area. However, it will be
* enough for most of the use cases.
*/
if (skip_hole && data_pos < old_pos) {
data_pos = vfs_llseek(old_file, old_pos, SEEK_DATA);
if (data_pos > old_pos) {
hole_len = data_pos - old_pos;
len -= hole_len;
old_pos = new_pos = data_pos;
continue;
} else if (data_pos == -ENXIO) {
break;
} else if (data_pos < 0) {
skip_hole = false;
}
}
bytes = do_splice_direct(old_file, &old_pos,
new_file, &new_pos,
this_len, SPLICE_F_MOVE);
if (bytes <= 0) {
error = bytes;
break;
}
WARN_ON(old_pos != new_pos);
len -= bytes;
}
out:
if (!error && ovl_should_sync(ofs))
error = vfs_fsync(new_file, 0);
fput(new_file);
out_fput:
fput(old_file);
return error;
}
static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat)
{
struct iattr attr = {
.ia_valid = ATTR_SIZE,
.ia_size = stat->size,
};
return notify_change(&init_user_ns, upperdentry, &attr, NULL);
}
static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
{
struct iattr attr = {
.ia_valid =
ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
.ia_atime = stat->atime,
.ia_mtime = stat->mtime,
};
return notify_change(&init_user_ns, upperdentry, &attr, NULL);
}
int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
{
int err = 0;
if (!S_ISLNK(stat->mode)) {
struct iattr attr = {
.ia_valid = ATTR_MODE,
.ia_mode = stat->mode,
};
err = notify_change(&init_user_ns, upperdentry, &attr, NULL);
}
if (!err) {
struct iattr attr = {
.ia_valid = ATTR_UID | ATTR_GID,
.ia_uid = stat->uid,
.ia_gid = stat->gid,
};
err = notify_change(&init_user_ns, upperdentry, &attr, NULL);
}
if (!err)
ovl_set_timestamps(upperdentry, stat);
return err;
}
struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real,
bool is_upper)
{
struct ovl_fh *fh;
int fh_type, dwords;
int buflen = MAX_HANDLE_SZ;
uuid_t *uuid = &real->d_sb->s_uuid;
int err;
/* Make sure the real fid stays 32bit aligned */
BUILD_BUG_ON(OVL_FH_FID_OFFSET % 4);
BUILD_BUG_ON(MAX_HANDLE_SZ + OVL_FH_FID_OFFSET > 255);
fh = kzalloc(buflen + OVL_FH_FID_OFFSET, GFP_KERNEL);
if (!fh)
return ERR_PTR(-ENOMEM);
/*
* We encode a non-connectable file handle for non-dir, because we
* only need to find the lower inode number and we don't want to pay
* the price or reconnecting the dentry.
*/
dwords = buflen >> 2;
fh_type = exportfs_encode_fh(real, (void *)fh->fb.fid, &dwords, 0);
buflen = (dwords << 2);
err = -EIO;
if (WARN_ON(fh_type < 0) ||
WARN_ON(buflen > MAX_HANDLE_SZ) ||
WARN_ON(fh_type == FILEID_INVALID))
goto out_err;
fh->fb.version = OVL_FH_VERSION;
fh->fb.magic = OVL_FH_MAGIC;
fh->fb.type = fh_type;
fh->fb.flags = OVL_FH_FLAG_CPU_ENDIAN;
/*
* When we will want to decode an overlay dentry from this handle
* and all layers are on the same fs, if we get a disconncted real
* dentry when we decode fid, the only way to tell if we should assign
* it to upperdentry or to lowerstack is by checking this flag.
*/
if (is_upper)
fh->fb.flags |= OVL_FH_FLAG_PATH_UPPER;
fh->fb.len = sizeof(fh->fb) + buflen;
if (ofs->config.uuid)
fh->fb.uuid = *uuid;
return fh;
out_err:
kfree(fh);
return ERR_PTR(err);
}
int ovl_set_origin(struct ovl_fs *ofs, struct dentry *dentry,
struct dentry *lower, struct dentry *upper)
{
const struct ovl_fh *fh = NULL;
int err;
/*
* When lower layer doesn't support export operations store a 'null' fh,
* so we can use the overlay.origin xattr to distignuish between a copy
* up and a pure upper inode.
*/
if (ovl_can_decode_fh(lower->d_sb)) {
fh = ovl_encode_real_fh(ofs, lower, false);
if (IS_ERR(fh))
return PTR_ERR(fh);
}
/*
* Do not fail when upper doesn't support xattrs.
*/
err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh->buf,
fh ? fh->fb.len : 0, 0);
kfree(fh);
/* Ignore -EPERM from setting "user.*" on symlink/special */
return err == -EPERM ? 0 : err;
}
/* Store file handle of @upper dir in @index dir entry */
static int ovl_set_upper_fh(struct ovl_fs *ofs, struct dentry *upper,
struct dentry *index)
{
const struct ovl_fh *fh;
int err;
fh = ovl_encode_real_fh(ofs, upper, true);
if (IS_ERR(fh))
return PTR_ERR(fh);
err = ovl_do_setxattr(ofs, index, OVL_XATTR_UPPER, fh->buf, fh->fb.len);
kfree(fh);
return err;
}
/*
* Create and install index entry.
*
* Caller must hold i_mutex on indexdir.
*/
static int ovl_create_index(struct dentry *dentry, struct dentry *origin,
struct dentry *upper)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
struct inode *dir = d_inode(indexdir);
struct dentry *index = NULL;
struct dentry *temp = NULL;
struct qstr name = { };
int err;
/*
* For now this is only used for creating index entry for directories,
* because non-dir are copied up directly to index and then hardlinked
* to upper dir.
*
* TODO: implement create index for non-dir, so we can call it when
* encoding file handle for non-dir in case index does not exist.
*/
if (WARN_ON(!d_is_dir(dentry)))
return -EIO;
/* Directory not expected to be indexed before copy up */
if (WARN_ON(ovl_test_flag(OVL_INDEX, d_inode(dentry))))
return -EIO;
err = ovl_get_index_name(ofs, origin, &name);
if (err)
return err;
temp = ovl_create_temp(indexdir, OVL_CATTR(S_IFDIR | 0));
err = PTR_ERR(temp);
if (IS_ERR(temp))
goto free_name;
err = ovl_set_upper_fh(ofs, upper, temp);
if (err)
goto out;
index = lookup_one_len(name.name, indexdir, name.len);
if (IS_ERR(index)) {
err = PTR_ERR(index);
} else {
err = ovl_do_rename(dir, temp, dir, index, 0);
dput(index);
}
out:
if (err)
ovl_cleanup(dir, temp);
dput(temp);
free_name:
kfree(name.name);
return err;
}
struct ovl_copy_up_ctx {
struct dentry *parent;
struct dentry *dentry;
struct path lowerpath;
struct kstat stat;
struct kstat pstat;
const char *link;
struct dentry *destdir;
struct qstr destname;
struct dentry *workdir;
bool origin;
bool indexed;
bool metacopy;
};
static int ovl_link_up(struct ovl_copy_up_ctx *c)
{
int err;
struct dentry *upper;
struct dentry *upperdir = ovl_dentry_upper(c->parent);
struct inode *udir = d_inode(upperdir);
/* Mark parent "impure" because it may now contain non-pure upper */
err = ovl_set_impure(c->parent, upperdir);
if (err)
return err;
err = ovl_set_nlink_lower(c->dentry);
if (err)
return err;
inode_lock_nested(udir, I_MUTEX_PARENT);
upper = lookup_one_len(c->dentry->d_name.name, upperdir,
c->dentry->d_name.len);
err = PTR_ERR(upper);
if (!IS_ERR(upper)) {
err = ovl_do_link(ovl_dentry_upper(c->dentry), udir, upper);
dput(upper);
if (!err) {
/* Restore timestamps on parent (best effort) */
ovl_set_timestamps(upperdir, &c->pstat);
ovl_dentry_set_upper_alias(c->dentry);
}
}
inode_unlock(udir);
if (err)
return err;
err = ovl_set_nlink_upper(c->dentry);
return err;
}
static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
{
struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
int err;
/*
* Copy up data first and then xattrs. Writing data after
* xattrs will remove security.capability xattr automatically.
*/
if (S_ISREG(c->stat.mode) && !c->metacopy) {
struct path upperpath, datapath;
ovl_path_upper(c->dentry, &upperpath);
if (WARN_ON(upperpath.dentry != NULL))
return -EIO;
upperpath.dentry = temp;
ovl_path_lowerdata(c->dentry, &datapath);
err = ovl_copy_up_data(ofs, &datapath, &upperpath,
c->stat.size);
if (err)
return err;
}
err = ovl_copy_xattr(c->dentry->d_sb, c->lowerpath.dentry, temp);
if (err)
return err;
/*
* Store identifier of lower inode in upper inode xattr to
* allow lookup of the copy up origin inode.
*
* Don't set origin when we are breaking the association with a lower
* hard link.
*/
if (c->origin) {
err = ovl_set_origin(ofs, c->dentry, c->lowerpath.dentry, temp);
if (err)
return err;
}
if (c->metacopy) {
err = ovl_check_setxattr(c->dentry, temp, OVL_XATTR_METACOPY,
NULL, 0, -EOPNOTSUPP);
if (err)
return err;
}
inode_lock(temp->d_inode);
if (S_ISREG(c->stat.mode))
err = ovl_set_size(temp, &c->stat);
if (!err)
err = ovl_set_attr(temp, &c->stat);
inode_unlock(temp->d_inode);
return err;
}
struct ovl_cu_creds {
const struct cred *old;
struct cred *new;
};
static int ovl_prep_cu_creds(struct dentry *dentry, struct ovl_cu_creds *cc)
{
int err;
cc->old = cc->new = NULL;
err = security_inode_copy_up(dentry, &cc->new);
if (err < 0)
return err;
if (cc->new)
cc->old = override_creds(cc->new);
return 0;
}
static void ovl_revert_cu_creds(struct ovl_cu_creds *cc)
{
if (cc->new) {
revert_creds(cc->old);
put_cred(cc->new);
}
}
/*
* Copyup using workdir to prepare temp file. Used when copying up directories,
* special files or when upper fs doesn't support O_TMPFILE.
*/
static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
{
struct inode *inode;
struct inode *udir = d_inode(c->destdir), *wdir = d_inode(c->workdir);
struct dentry *temp, *upper;
struct ovl_cu_creds cc;
int err;
struct ovl_cattr cattr = {
/* Can't properly set mode on creation because of the umask */
.mode = c->stat.mode & S_IFMT,
.rdev = c->stat.rdev,
.link = c->link
};
/* workdir and destdir could be the same when copying up to indexdir */
err = -EIO;
if (lock_rename(c->workdir, c->destdir) != NULL)
goto unlock;
err = ovl_prep_cu_creds(c->dentry, &cc);
if (err)
goto unlock;
temp = ovl_create_temp(c->workdir, &cattr);
ovl_revert_cu_creds(&cc);
err = PTR_ERR(temp);
if (IS_ERR(temp))
goto unlock;
err = ovl_copy_up_inode(c, temp);
if (err)
goto cleanup;
if (S_ISDIR(c->stat.mode) && c->indexed) {
err = ovl_create_index(c->dentry, c->lowerpath.dentry, temp);
if (err)
goto cleanup;
}
upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
err = PTR_ERR(upper);
if (IS_ERR(upper))
goto cleanup;
err = ovl_do_rename(wdir, temp, udir, upper, 0);
dput(upper);
if (err)
goto cleanup;
if (!c->metacopy)
ovl_set_upperdata(d_inode(c->dentry));
inode = d_inode(c->dentry);
ovl_inode_update(inode, temp);
if (S_ISDIR(inode->i_mode))
ovl_set_flag(OVL_WHITEOUTS, inode);
unlock:
unlock_rename(c->workdir, c->destdir);
return err;
cleanup:
ovl_cleanup(wdir, temp);
dput(temp);
goto unlock;
}
/* Copyup using O_TMPFILE which does not require cross dir locking */
static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
{
struct inode *udir = d_inode(c->destdir);
struct dentry *temp, *upper;
struct ovl_cu_creds cc;
int err;
err = ovl_prep_cu_creds(c->dentry, &cc);
if (err)
return err;
temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
ovl_revert_cu_creds(&cc);
if (IS_ERR(temp))
return PTR_ERR(temp);
err = ovl_copy_up_inode(c, temp);
if (err)
goto out_dput;
inode_lock_nested(udir, I_MUTEX_PARENT);
upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
err = PTR_ERR(upper);
if (!IS_ERR(upper)) {
err = ovl_do_link(temp, udir, upper);
dput(upper);
}
inode_unlock(udir);
if (err)
goto out_dput;
if (!c->metacopy)
ovl_set_upperdata(d_inode(c->dentry));
ovl_inode_update(d_inode(c->dentry), temp);
return 0;
out_dput:
dput(temp);
return err;
}
/*
* Copy up a single dentry
*
* All renames start with copy up of source if necessary. The actual
* rename will only proceed once the copy up was successful. Copy up uses
* upper parent i_mutex for exclusion. Since rename can change d_parent it
* is possible that the copy up will lock the old parent. At that point
* the file will have already been copied up anyway.
*/
static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
{
int err;
struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
bool to_index = false;
/*
* Indexed non-dir is copied up directly to the index entry and then
* hardlinked to upper dir. Indexed dir is copied up to indexdir,
* then index entry is created and then copied up dir installed.
* Copying dir up to indexdir instead of workdir simplifies locking.
*/
if (ovl_need_index(c->dentry)) {
c->indexed = true;
if (S_ISDIR(c->stat.mode))
c->workdir = ovl_indexdir(c->dentry->d_sb);
else
to_index = true;
}
if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || to_index)
c->origin = true;
if (to_index) {
c->destdir = ovl_indexdir(c->dentry->d_sb);
err = ovl_get_index_name(ofs, c->lowerpath.dentry, &c->destname);
if (err)
return err;
} else if (WARN_ON(!c->parent)) {
/* Disconnected dentry must be copied up to index dir */
return -EIO;
} else {
/*
* Mark parent "impure" because it may now contain non-pure
* upper
*/
err = ovl_set_impure(c->parent, c->destdir);
if (err)
return err;
}
/* Should we copyup with O_TMPFILE or with workdir? */
if (S_ISREG(c->stat.mode) && ofs->tmpfile)
err = ovl_copy_up_tmpfile(c);
else
err = ovl_copy_up_workdir(c);
if (err)
goto out;
if (c->indexed)
ovl_set_flag(OVL_INDEX, d_inode(c->dentry));
if (to_index) {
/* Initialize nlink for copy up of disconnected dentry */
err = ovl_set_nlink_upper(c->dentry);
} else {
struct inode *udir = d_inode(c->destdir);
/* Restore timestamps on parent (best effort) */
inode_lock(udir);
ovl_set_timestamps(c->destdir, &c->pstat);
inode_unlock(udir);
ovl_dentry_set_upper_alias(c->dentry);
}
out:
if (to_index)
kfree(c->destname.name);
return err;
}
static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode,
int flags)
{
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
if (!ofs->config.metacopy)
return false;
if (!S_ISREG(mode))
return false;
if (flags && ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC)))
return false;
return true;
}
static ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value)
{
ssize_t res;
char *buf;
res = vfs_getxattr(&init_user_ns, dentry, name, NULL, 0);
if (res == -ENODATA || res == -EOPNOTSUPP)
res = 0;
if (res > 0) {
buf = kzalloc(res, GFP_KERNEL);
if (!buf)
return -ENOMEM;
res = vfs_getxattr(&init_user_ns, dentry, name, buf, res);
if (res < 0)
kfree(buf);
else
*value = buf;
}
return res;
}
/* Copy up data of an inode which was copied up metadata only in the past. */
static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
{
struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
struct path upperpath, datapath;
int err;
char *capability = NULL;
ssize_t cap_size;
ovl_path_upper(c->dentry, &upperpath);
if (WARN_ON(upperpath.dentry == NULL))
return -EIO;
ovl_path_lowerdata(c->dentry, &datapath);
if (WARN_ON(datapath.dentry == NULL))
return -EIO;
if (c->stat.size) {
err = cap_size = ovl_getxattr(upperpath.dentry, XATTR_NAME_CAPS,
&capability);
if (cap_size < 0)
goto out;
}
err = ovl_copy_up_data(ofs, &datapath, &upperpath, c->stat.size);
if (err)
goto out_free;
/*
* Writing to upper file will clear security.capability xattr. We
* don't want that to happen for normal copy-up operation.
*/
if (capability) {
err = vfs_setxattr(&init_user_ns, upperpath.dentry,
XATTR_NAME_CAPS, capability, cap_size, 0);
if (err)
goto out_free;
}
err = ovl_do_removexattr(ofs, upperpath.dentry, OVL_XATTR_METACOPY);
if (err)
goto out_free;
ovl_set_upperdata(d_inode(c->dentry));
out_free:
kfree(capability);
out:
return err;
}
static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
int flags)
{
int err;
DEFINE_DELAYED_CALL(done);
struct path parentpath;
struct ovl_copy_up_ctx ctx = {
.parent = parent,
.dentry = dentry,
.workdir = ovl_workdir(dentry),
};
if (WARN_ON(!ctx.workdir))
return -EROFS;
ovl_path_lower(dentry, &ctx.lowerpath);
err = vfs_getattr(&ctx.lowerpath, &ctx.stat,
STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
if (err)
return err;
ctx.metacopy = ovl_need_meta_copy_up(dentry, ctx.stat.mode, flags);
if (parent) {
ovl_path_upper(parent, &parentpath);
ctx.destdir = parentpath.dentry;
ctx.destname = dentry->d_name;
err = vfs_getattr(&parentpath, &ctx.pstat,
STATX_ATIME | STATX_MTIME,
AT_STATX_SYNC_AS_STAT);
if (err)
return err;
}
/* maybe truncate regular file. this has no effect on dirs */
if (flags & O_TRUNC)
ctx.stat.size = 0;
if (S_ISLNK(ctx.stat.mode)) {
ctx.link = vfs_get_link(ctx.lowerpath.dentry, &done);
if (IS_ERR(ctx.link))
return PTR_ERR(ctx.link);
}
err = ovl_copy_up_start(dentry, flags);
/* err < 0: interrupted, err > 0: raced with another copy-up */
if (unlikely(err)) {
if (err > 0)
err = 0;
} else {
if (!ovl_dentry_upper(dentry))
err = ovl_do_copy_up(&ctx);
if (!err && parent && !ovl_dentry_has_upper_alias(dentry))
err = ovl_link_up(&ctx);
if (!err && ovl_dentry_needs_data_copy_up_locked(dentry, flags))
err = ovl_copy_up_meta_inode_data(&ctx);
ovl_copy_up_end(dentry);
}
do_delayed_call(&done);
return err;
}
static int ovl_copy_up_flags(struct dentry *dentry, int flags)
{
int err = 0;
const struct cred *old_cred;
bool disconnected = (dentry->d_flags & DCACHE_DISCONNECTED);
/*
* With NFS export, copy up can get called for a disconnected non-dir.
* In this case, we will copy up lower inode to index dir without
* linking it to upper dir.
*/
if (WARN_ON(disconnected && d_is_dir(dentry)))
return -EIO;
old_cred = ovl_override_creds(dentry->d_sb);
while (!err) {
struct dentry *next;
struct dentry *parent = NULL;
if (ovl_already_copied_up(dentry, flags))
break;
next = dget(dentry);
/* find the topmost dentry not yet copied up */
for (; !disconnected;) {
parent = dget_parent(next);
if (ovl_dentry_upper(parent))
break;
dput(next);
next = parent;
}
err = ovl_copy_up_one(parent, next, flags);
dput(parent);
dput(next);
}
revert_creds(old_cred);
return err;
}
static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
{
/* Copy up of disconnected dentry does not set upper alias */
if (ovl_already_copied_up(dentry, flags))
return false;
if (special_file(d_inode(dentry)->i_mode))
return false;
if (!ovl_open_flags_need_copy_up(flags))
return false;
return true;
}
int ovl_maybe_copy_up(struct dentry *dentry, int flags)
{
int err = 0;
if (ovl_open_need_copy_up(dentry, flags)) {
err = ovl_want_write(dentry);
if (!err) {
err = ovl_copy_up_flags(dentry, flags);
ovl_drop_write(dentry);
}
}
return err;
}
int ovl_copy_up_with_data(struct dentry *dentry)
{
return ovl_copy_up_flags(dentry, O_WRONLY);
}
int ovl_copy_up(struct dentry *dentry)
{
return ovl_copy_up_flags(dentry, 0);
}
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