/*
* decide if a new whiteout for @dentry is necessary or not.
* when it is necessary, prepare the parent dir for the upper branch whose
* branch index is @bcpup for creation. the actual creation of the whiteout will
* be done by caller.
* return value:
* 0: wh is unnecessary
* plus: wh is necessary
* minus: error
*/
int au_wr_dir_need_wh(struct dentry *dentry, int isdir, aufs_bindex_t *bcpup)
{
int need_wh, err;
aufs_bindex_t bstart;
struct super_block *sb;
sb = dentry->d_sb;
bstart = au_dbstart(dentry);
if (*bcpup < 0) {
*bcpup = bstart;
if (au_test_ro(sb, bstart, dentry->d_inode)) {
err = AuWbrCopyup(au_sbi(sb), dentry);
*bcpup = err;
if (unlikely(err < 0))
goto out;
}
} else
AuDebugOn(bstart < *bcpup
|| au_test_ro(sb, *bcpup, dentry->d_inode));
AuDbg("bcpup %d, bstart %d\n", *bcpup, bstart);
if (*bcpup != bstart) {
err = au_cpup_dirs(dentry, *bcpup);
if (unlikely(err))
goto out;
need_wh = 1;
} else {
struct au_dinfo *dinfo, *tmp;
need_wh = -ENOMEM;
dinfo = au_di(dentry);
tmp = au_di_alloc(sb, AuLsc_DI_TMP);
if (tmp) {
au_di_cp(tmp, dinfo);
au_di_swap(tmp, dinfo);
/* returns the number of positive dentries */
need_wh = au_lkup_dentry(dentry, bstart + 1, /*type*/0,
/*nd*/NULL);
au_di_swap(tmp, dinfo);
au_rw_write_unlock(&tmp->di_rwsem);
au_di_free(tmp);
}
}
AuDbg("need_wh %d\n", need_wh);
err = need_wh;
out:
return err;
}
int au_di_init(struct dentry *dentry)
{
int err;
struct super_block *sb;
struct au_dinfo *dinfo;
err = 0;
sb = dentry->d_sb;
dinfo = au_di_alloc(sb, AuLsc_DI_CHILD);
if (dinfo) {
atomic_set(&dinfo->di_generation, au_sigen(sb));
/* smp_mb(); */ /* atomic_set */
dentry->d_fsdata = dinfo;
} else
err = -ENOMEM;
return err;
}
static int au_mvd_args_intermediate(const unsigned char dmsg,
struct au_mvd_args *a)
{
int err;
struct au_dinfo *dinfo, *tmp;
/* lookup the next lower positive entry */
err = -ENOMEM;
tmp = au_di_alloc(a->sb, AuLsc_DI_TMP);
if (unlikely(!tmp))
goto out;
a->bfound = -1;
a->bwh = -1;
dinfo = au_di(a->dentry);
au_di_cp(tmp, dinfo);
au_di_swap(tmp, dinfo);
/* returns the number of positive dentries */
err = au_lkup_dentry(a->dentry, a->mvd_bsrc + 1, /*type*/0);
if (!err)
a->bwh = au_dbwh(a->dentry);
else if (err > 0)
a->bfound = au_dbstart(a->dentry);
au_di_swap(tmp, dinfo);
au_rw_write_unlock(&tmp->di_rwsem);
au_di_free(tmp);
if (unlikely(err < 0))
AU_MVD_PR(dmsg, "failed look-up lower\n");
/*
* here, we have these cases.
* bfound == -1
* no positive dentry under bsrc. there are more sub-cases.
* bwh < 0
* there no whiteout, we can safely move-down.
* bwh <= bsrc
* impossible
* bsrc < bwh && bwh < bdst
* there is a whiteout on RO branch. cannot proceed.
* bwh == bdst
* there is a whiteout on the RW target branch. it should
* be removed.
* bdst < bwh
* there is a whiteout somewhere unrelated branch.
* -1 < bfound && bfound <= bsrc
* impossible.
* bfound < bdst
* found, but it is on RO branch between bsrc and bdst. cannot
* proceed.
* bfound == bdst
* found, replace it if AUFS_MVDOWN_FORCE is set. otherwise return
* error.
* bdst < bfound
* found, after we create the file on bdst, it will be hidden.
*/
AuDebugOn(a->bfound == -1
&& a->bwh != -1
&& a->bwh <= a->mvd_bsrc);
AuDebugOn(-1 < a->bfound
&& a->bfound <= a->mvd_bsrc);
err = -EINVAL;
if (a->bfound == -1
&& a->mvd_bsrc < a->bwh
&& a->bwh != -1
&& a->bwh < a->mvd_bdst) {
a->mvd_errno = EAU_MVDOWN_WHITEOUT;
AU_MVD_PR(dmsg, "bsrc %d, bdst %d, bfound %d, bwh %d\n",
a->mvd_bsrc, a->mvd_bdst, a->bfound, a->bwh);
goto out;
} else if (a->bfound != -1 && a->bfound < a->mvd_bdst) {
a->mvd_errno = EAU_MVDOWN_UPPER;
AU_MVD_PR(dmsg, "bdst %d, bfound %d\n",
a->mvd_bdst, a->bfound);
goto out;
}
err = 0; /* success */
out:
AuTraceErr(err);
return err;
}
int au_refresh_dentry(struct dentry *dentry, struct dentry *parent)
{
int err, ebrange;
unsigned int sigen;
struct au_dinfo *dinfo, *tmp;
struct super_block *sb;
struct inode *inode;
DiMustWriteLock(dentry);
AuDebugOn(IS_ROOT(dentry));
AuDebugOn(!parent->d_inode);
sb = dentry->d_sb;
inode = dentry->d_inode;
sigen = au_sigen(sb);
err = au_digen_test(parent, sigen);
if (unlikely(err))
goto out;
dinfo = au_di(dentry);
err = au_di_realloc(dinfo, au_sbend(sb) + 1);
if (unlikely(err))
goto out;
ebrange = au_dbrange_test(dentry);
if (!ebrange)
ebrange = au_do_refresh_hdentry(dentry, parent);
if (d_unhashed(dentry) || ebrange) {
AuDebugOn(au_dbstart(dentry) < 0 && au_dbend(dentry) >= 0);
if (inode)
err = au_refresh_hinode_self(inode);
au_dbg_verify_dinode(dentry);
if (!err)
goto out_dgen; /* success */
goto out;
}
/* temporary dinfo */
AuDbgDentry(dentry);
err = -ENOMEM;
tmp = au_di_alloc(sb, AuLsc_DI_TMP);
if (unlikely(!tmp))
goto out;
au_di_swap(tmp, dinfo);
/* returns the number of positive dentries */
/*
* if current working dir is removed, it returns an error.
* but the dentry is legal.
*/
err = au_lkup_dentry(dentry, /*bstart*/0, /*type*/0, /*nd*/NULL);
AuDbgDentry(dentry);
au_di_swap(tmp, dinfo);
if (err == -ENOENT)
err = 0;
if (err >= 0) {
/* compare/refresh by dinfo */
AuDbgDentry(dentry);
err = au_refresh_by_dinfo(dentry, dinfo, tmp);
au_dbg_verify_dinode(dentry);
AuTraceErr(err);
}
au_rw_write_unlock(&tmp->di_rwsem);
au_di_free(tmp);
if (unlikely(err))
goto out;
out_dgen:
au_update_digen(dentry);
out:
if (unlikely(err && !(dentry->d_flags & DCACHE_NFSFS_RENAMED))) {
AuIOErr("failed refreshing %.*s, %d\n",
AuDLNPair(dentry), err);
AuDbgDentry(dentry);
}
AuTraceErr(err);
return err;
}
