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cifs: switch build_path_from_dentry() to using dentry_path_raw() 

The cost is that we might need to flip '/' to '\\' in more than
just the prefix.  Needs profiling, but I suspect that we won't
get slowdown on that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Al Viro 2021-03-05 21:53:48 -05:00 committed by Steve French
parent f6a9bc336b
commit 991e72eb0e
1 changed files with 23 additions and 62 deletions
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85
fs/cifs/dir.c
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@ -93,20 +93,16 @@ char *
build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
bool prefix)
{
struct dentry *temp;
int namelen;
int dfsplen;
int pplen = 0;
char *full_path = page;
char dirsep;
struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
unsigned seq;
char dirsep = CIFS_DIR_SEP(cifs_sb);
char *s;
if (unlikely(!page))
return ERR_PTR(-ENOMEM);
dirsep = CIFS_DIR_SEP(cifs_sb);
if (prefix)
dfsplen = strnlen(tcon->treeName, MAX_TREE_SIZE + 1);
else
@ -115,74 +111,39 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH)
pplen = cifs_sb->prepath ? strlen(cifs_sb->prepath) + 1 : 0;
cifs_bp_rename_retry:
namelen = dfsplen + pplen;
seq = read_seqbegin(&rename_lock);
rcu_read_lock();
for (temp = direntry; !IS_ROOT(temp);) {
namelen += (1 + temp->d_name.len);
temp = temp->d_parent;
}
rcu_read_unlock();
if (namelen >= PAGE_SIZE)
s = dentry_path_raw(direntry, page, PAGE_SIZE);
if (IS_ERR(s))
return s;
if (!s[1]) // for root we want "", not "/"
s++;
if (s < (char *)page + pplen + dfsplen)
return ERR_PTR(-ENAMETOOLONG);
full_path[namelen] = 0; /* trailing null */
rcu_read_lock();
for (temp = direntry; !IS_ROOT(temp);) {
spin_lock(&temp->d_lock);
namelen -= 1 + temp->d_name.len;
if (namelen < 0) {
spin_unlock(&temp->d_lock);
break;
} else {
full_path[namelen] = dirsep;
strncpy(full_path + namelen + 1, temp->d_name.name,
temp->d_name.len);
cifs_dbg(FYI, "name: %s\n", full_path + namelen);
}
spin_unlock(&temp->d_lock);
temp = temp->d_parent;
}
rcu_read_unlock();
if (namelen != dfsplen + pplen || read_seqretry(&rename_lock, seq)) {
cifs_dbg(FYI, "did not end path lookup where expected. namelen=%ddfsplen=%d\n",
namelen, dfsplen);
/* presumably this is only possible if racing with a rename
of one of the parent directories (we can not lock the dentries
above us to prevent this, but retrying should be harmless) */
goto cifs_bp_rename_retry;
}
/* DIR_SEP already set for byte 0 / vs \ but not for
subsequent slashes in prepath which currently must
be entered the right way - not sure if there is an alternative
since the '\' is a valid posix character so we can not switch
those safely to '/' if any are found in the middle of the prepath */
/* BB test paths to Windows with '/' in the midst of prepath */
if (pplen) {
int i;
cifs_dbg(FYI, "using cifs_sb prepath <%s>\n", cifs_sb->prepath);
memcpy(full_path+dfsplen+1, cifs_sb->prepath, pplen-1);
full_path[dfsplen] = dirsep;
for (i = 0; i < pplen-1; i++)
if (full_path[dfsplen+1+i] == '/')
full_path[dfsplen+1+i] = CIFS_DIR_SEP(cifs_sb);
s -= pplen;
memcpy(s + 1, cifs_sb->prepath, pplen - 1);
*s = '/';
}
if (dirsep != '/') {
/* BB test paths to Windows with '/' in the midst of prepath */
char *p;
for (p = s; *p; p++)
if (*p == '/')
*p = dirsep;
}
if (dfsplen) {
strncpy(full_path, tcon->treeName, dfsplen);
s -= dfsplen;
memcpy(s, tcon->treeName, dfsplen);
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) {
int i;
for (i = 0; i < dfsplen; i++) {
if (full_path[i] == '\\')
full_path[i] = '/';
if (s[i] == '\\')
s[i] = '/';
}
}
}
return full_path;
return s;
}
/*