The commit is pushed to "branch-rh7-3.10.0-327.28.2.vz7.17.x-ovz" and will 
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.28.2.vz7.17.9
------>
commit 00ebb1860eff85759f1b43d795c328311c684b0e
Author: Pavel Tikhomirov <ptikhomi...@virtuozzo.com>
Date:   Fri Sep 23 18:03:26 2016 +0400

    pfcache: hide trusted.pfcache from listxattr
    
    In SyS_listxattr -> listxattr -> ext4_listxattr ->
    ext4_xattr_list_entries we choose list handler for
    each ext4_xattr_entry based on e_name_index, and as
    for trusted.pfcache index is EXT4_XATTR_INDEX_TRUSTED,
    we chouse ext4_xattr_trusted_list which always prints
    xattr to the list.
    
    When there is no PFCACHE_CSUM on superblock we do
    not allow get/set trusted.pfcache, so hide it from
    list too. To do so - change it's e_name_index to new
    EXT4_XATTR_INDEX_TRUSTED_CSUM and thus use
    ext4_xattr_trusted_csum_list. Check PFCACHE_CSUM
    in it, and if no - do not print xattr to list.
    
    Also do not allow list without global CAP_SYS_ADMIN,
    as we do not allow set/get without it.
    
    Test:
    
    TEST_FILE=/vz/root/101/testfile
    rm -f $TEST_FILE
    touch $TEST_FILE
    TEST_SHA1=`sha1sum $TEST_FILE | awk '{print $1}'`
    setfattr -n trusted.pfcache -v $TEST_SHA1 $TEST_FILE
    setfattr -n trusted.test -v test $TEST_FILE
    getfattr -d -m trusted $TEST_FILE
    
      trusted.pfcache="da39a3ee5e6b4b0d3255bfef95601890afd80709"
      trusted.test="test"
    
    mount -oremount,nopfcache_csum /vz/root/101
    getfattr -d -m trusted $TEST_FILE
    
      trusted.test="test"
    
    v2: hide only if nopfcache_csum
    
    https://jira.sw.ru/browse/PSBM-52180
    Signed-off-by: Pavel Tikhomirov <ptikhomi...@virtuozzo.com>
---
 fs/ext4/pfcache.c | 45 ++++++++++++++++++++++++++++++---------------
 fs/ext4/xattr.c   |  1 +
 fs/ext4/xattr.h   |  1 +
 3 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/fs/ext4/pfcache.c b/fs/ext4/pfcache.c
index ff2300b..52bd886 100644
--- a/fs/ext4/pfcache.c
+++ b/fs/ext4/pfcache.c
@@ -441,8 +441,8 @@ int ext4_load_data_csum(struct inode *inode)
 {
        int ret;
 
-       ret = ext4_xattr_get(inode, EXT4_XATTR_INDEX_TRUSTED,
-                       EXT4_DATA_CSUM_NAME, EXT4_I(inode)->i_data_csum,
+       ret = ext4_xattr_get(inode, EXT4_XATTR_INDEX_TRUSTED_CSUM,
+                       "", EXT4_I(inode)->i_data_csum,
                        EXT4_DATA_CSUM_SIZE);
        if (ret < 0)
                return ret;
@@ -482,8 +482,8 @@ static int ext4_save_data_csum(struct inode *inode, u8 
*csum)
        if (ret)
                return ret;
 
-       return ext4_xattr_set(inode, EXT4_XATTR_INDEX_TRUSTED,
-                       EXT4_DATA_CSUM_NAME, EXT4_I(inode)->i_data_csum,
+       return ext4_xattr_set(inode, EXT4_XATTR_INDEX_TRUSTED_CSUM,
+                       "", EXT4_I(inode)->i_data_csum,
                        EXT4_DATA_CSUM_SIZE, 0);
 }
 
@@ -492,8 +492,8 @@ void ext4_load_dir_csum(struct inode *inode)
        char value[EXT4_DIR_CSUM_VALUE_LEN];
        int ret;
 
-       ret = ext4_xattr_get(inode, EXT4_XATTR_INDEX_TRUSTED,
-                            EXT4_DATA_CSUM_NAME, value, sizeof(value));
+       ret = ext4_xattr_get(inode, EXT4_XATTR_INDEX_TRUSTED_CSUM,
+                            "", value, sizeof(value));
        if (ret == EXT4_DIR_CSUM_VALUE_LEN &&
            !strncmp(value, EXT4_DIR_CSUM_VALUE, sizeof(value)))
                ext4_set_inode_state(inode, EXT4_STATE_PFCACHE_CSUM);
@@ -502,8 +502,8 @@ void ext4_load_dir_csum(struct inode *inode)
 void ext4_save_dir_csum(struct inode *inode)
 {
        ext4_set_inode_state(inode, EXT4_STATE_PFCACHE_CSUM);
-       ext4_xattr_set(inode, EXT4_XATTR_INDEX_TRUSTED,
-                       EXT4_DATA_CSUM_NAME,
+       ext4_xattr_set(inode, EXT4_XATTR_INDEX_TRUSTED_CSUM,
+                       "",
                        EXT4_DIR_CSUM_VALUE,
                        EXT4_DIR_CSUM_VALUE_LEN, 0);
 }
@@ -516,8 +516,8 @@ void ext4_truncate_data_csum(struct inode *inode, loff_t 
pos)
 
        if (EXT4_I(inode)->i_data_csum_end < 0) {
                WARN_ON(journal_current_handle());
-               ext4_xattr_set(inode, EXT4_XATTR_INDEX_TRUSTED,
-                               EXT4_DATA_CSUM_NAME, NULL, 0, 0);
+               ext4_xattr_set(inode, EXT4_XATTR_INDEX_TRUSTED_CSUM,
+                               "", NULL, 0, 0);
                ext4_close_pfcache(inode);
        }
        spin_lock(&inode->i_lock);
@@ -658,8 +658,8 @@ static int ext4_xattr_trusted_csum_get(struct dentry 
*dentry, const char *name,
                return -EPERM;
 
        if (S_ISDIR(inode->i_mode))
-               return ext4_xattr_get(inode, EXT4_XATTR_INDEX_TRUSTED,
-                                     EXT4_DATA_CSUM_NAME, buffer, size);
+               return ext4_xattr_get(inode, EXT4_XATTR_INDEX_TRUSTED_CSUM,
+                                     "", buffer, size);
 
        if (!S_ISREG(inode->i_mode))
                return -ENODATA;
@@ -717,8 +717,8 @@ static int ext4_xattr_trusted_csum_set(struct dentry 
*dentry, const char *name,
                else
                        return -EINVAL;
 
-               return ext4_xattr_set(inode, EXT4_XATTR_INDEX_TRUSTED,
-                                     EXT4_DATA_CSUM_NAME, value, size, flags);
+               return ext4_xattr_set(inode, EXT4_XATTR_INDEX_TRUSTED_CSUM,
+                                     "", value, size, flags);
        }
 
        if (!S_ISREG(inode->i_mode))
@@ -763,7 +763,22 @@ static size_t
 ext4_xattr_trusted_csum_list(struct dentry *dentry, char *list, size_t 
list_size,
                             const char *name, size_t name_len, int 
handler_flags)
 {
-       return 0;
+       struct inode *inode = dentry->d_inode;
+       const size_t len = XATTR_TRUSTED_CSUM_PREFIX_LEN + 1;
+
+       BUG_ON(name_len);
+
+       if (!test_opt2(inode->i_sb, PFCACHE_CSUM))
+               return 0;
+
+       if (!capable(CAP_SYS_ADMIN))
+               return 0;
+
+       if (list && len <= list_size) {
+               memcpy(list, XATTR_TRUSTED_CSUM_PREFIX, 
XATTR_TRUSTED_CSUM_PREFIX_LEN);
+               list[len] = '\0';
+       }
+       return len;
 }
 
 struct xattr_handler ext4_xattr_trusted_csum_handler = {
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 5dabf58..81b5534 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -102,6 +102,7 @@ static const struct xattr_handler *ext4_xattr_handler_map[] 
= {
 #ifdef CONFIG_EXT4_FS_SECURITY
        [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
 #endif
+       [EXT4_XATTR_INDEX_TRUSTED_CSUM]      = &ext4_xattr_trusted_csum_handler,
 };
 
 const struct xattr_handler *ext4_xattr_handlers[] = {
diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index c767dbd..f6af6c9 100644
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -23,6 +23,7 @@
 #define EXT4_XATTR_INDEX_SECURITY              6
 #define EXT4_XATTR_INDEX_SYSTEM                        7
 #define EXT4_XATTR_INDEX_RICHACL               8
+#define EXT4_XATTR_INDEX_TRUSTED_CSUM          9
 
 struct ext4_xattr_header {
        __le32  h_magic;        /* magic number for identification */
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