posix: placeholders for GFID to path conversion

what?
=====
    The following is an attempt to generate the paths of a file when
    only its gfid is known.

    To find the path of a directory, the symlink handle to the
    directory maintained in  the ".glusterfs" backend directory is
    read. The symlink handle is generated using the gfid of the
    directory. It (handle) contains the directory's name and parent
    gfid, which are used to recursively construct the absolute path as
    seen by the user from the mount point.

    A similar approach cannot be used for a regular file or a symbolic
    link since its hardlink handle, generated using its gfid, doesn't
    contain its parent gfid and basename. So xattrs are set to store
    the parent gfids and the number of hardlinks to a file or a
    symlink having the same parent gfid.  When an user/application
    requests for the paths of a regular file or a symlink with
    multiple hardlinks, using the parent gfids stored in the xattrs,
    the paths of the parent directories are generated as mentioned
    earlier. The base names of the hardlinks (with the same parent
    gfid) are determined by matching the actual backend inode numbers
    of each entry in the parent directory with that of the hardlink
    handle.

    Xattr is set on a regular file, link, and symbolic link as
    follows, Xattr name : trusted.pgfid.<pargfidstr> Xattr value :
    <number of hardlinks to a regular file/symlink with the same
    parentgfid>

    If a regular file, hard link, symbolic link is created then an
    xattr in the above format is set in the backend.

how to use?
===========
    This functionality can be used through getxattr interface. Two
    keys - glusterfs.ancestry.dentry and glusterfs.ancestry.path - enable
    usage of this functionality. A successful getxattr will have the
    result stored under same keys. Values will be,

    glusterfs.ancestry.dentry:
    --------------------------
    A linked list of gf-dirent structures for all possible paths from
    root to this gfid. If there are multiple paths, the linked-list
    will be a series of paths one after another. Each path will be a
    series of dentries representing all components of the path. This
    key is primarily for internal usage within glusterfs.

    glusterfs.ancestry.path:
    ------------------------
    A string containing all possible paths from root to this gfid.
    Multiple hardlinks of a file or a symlink are displayed as a colon
    seperated list (this could interfere with path components
    containing ':').

    e.g. If there is a file "file1" in root directory with two hardlinks,
         "/dir2/link2tofile1" and "/dir1/link1tofile1", then

         [root@alpha gfsmntpt]# getfattr -n glusterfs.ancestry.path -e text
          file1
          glusterfs.ancestry.path="/file1:/dir2/link2tofile1:/dir1/link1tofile1"

    Thanks Amar, Avati and Venky for the inputs.

Original Author: Ramana Raja <rraja@redhat.com>
BUG: 990028
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
Change-Id: I0eaa9101e333e0c1f66ccefd9e95944dd4a27497
Reviewed-on: http://review.gluster.org/5951
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 156 insertions, 0 deletions

diff --git a/tests/bugs/bug-990028.t b/tests/bugs/bug-990028.t
new file mode 100755
index 00000000000..ece7235cd96
--- /dev/null
+++ b/tests/bugs/bug-990028.t
@@ -0,0 +1,156 @@
+#!/bin/bash
+
+. $(dirname $0)/../include.rc
+. $(dirname $0)/../fileio.rc
+
+cleanup;
+
+TESTS_EXPECTED_IN_LOOP=153
+
+function __init()
+{
+    TEST glusterd
+    TEST pidof glusterd
+    TEST $CLI volume info;
+
+    TEST $CLI volume create $V0 $H0:$B0/brick
+
+    EXPECT 'Created' volinfo_field $V0 'Status';
+
+    TEST $CLI volume start $V0
+
+    TEST glusterfs --volfile-id=$V0 --volfile-server=$H0 $M0
+
+    TEST $CLI volume quota $V0 enable
+    sleep 15
+}
+
+#CASE-1
+#checking pgfid under same directory
+function links_in_same_directory()
+{
+    # create a file file1
+    TEST touch $M0/file1
+
+    # create 50 hardlinks for file1
+    for i in `seq 2 50`; do
+        TEST_IN_LOOP ln $M0/file1 $M0/file$i
+    done
+
+    # store the pgfid of file1 in PGFID_FILE1 [should be 50 now (0x000000032)]
+    PGFID_FILE1=`getfattr -m "trusted.pgfid.*" -de hex  $B0/brick/file1 2>&1 | grep "trusted.pgfid" | gawk -F '=' '{print $2}'`
+
+    # compare the pgfid(link value ) of each  hard links are equal or not
+    for i in `seq  2 50`; do
+        TEMP=`getfattr -m "trusted.pgfid.*" -de hex $B0/brick/file$i 2>&1 | grep "trusted.pgfid" | gawk -F '=' '{print $2}'`
+        TEST_IN_LOOP [ $PGFID_FILE1 = $TEMP ]
+    done
+
+    # check if no of links value is 50 or not
+    TEST [ $PGFID_FILE1 = "0x00000032" ]
+
+    # unlink file 2 to 50
+    for i in `seq 2 50`; do
+        TEST_IN_LOOP unlink $M0/file$i;
+    done
+
+    # now check if pgfid value is 1 or not
+    PGFID_FILE1=`getfattr -m "trusted.pgfid.*" -de hex  $B0/brick/file1 2>&1 | grep "trusted.pgfid" | gawk -F '=' '{print $2}'`;
+
+    TEST [ $PGFID_FILE1 = "0x00000001" ]
+
+    TEST rm -f $M0/*
+}
+
+##checking pgfid under diff directories
+function links_across_directories()
+{
+    TEST mkdir $M0/dir1 $M0/dir2;
+
+    # create a file in dir1
+    TEST touch $M0/dir1/file1;
+
+    # create  hard link for file1 in dir2
+    TEST ln $M0/dir1/file1 $M0/dir2/file2;
+
+    #first check is to find whether there are two pgfids or not
+    LINES=`getfattr -m "trusted.pgfid.*" -de hex $B0/brick/dir1/file1 2>&1 | grep "trusted.pgfid" | wc -l`
+    TEST [ $LINES = 2 ]
+
+    for i in $(seq 1  2); do
+        HL=`getfattr -m "trusted.pgfid.*" -de hex $B0/brick/dir$i/file$i 2>&1 | grep "trusted.pgfid" | cut -d$'\n' -f$i | cut -d'=' -f2`        
+        TEST_IN_LOOP [ $HL = "0x00000001" ]
+    done
+
+    #now unlink file2 and check the pgfid of file1
+    #1. no. of pgfid should be one
+    #2. no. of hard link should be one
+    TEST unlink $M0/dir2/file2
+
+    LINES=`getfattr -m "trusted.pgfid.*" -de hex $B0/brick/dir1/file1 2>&1 | grep "trusted.pgfid" | wc -l`
+    TEST [ $LINES == 1 ]
+
+    #next to check is to whether they contain hard link value of one or not
+    HL=`getfattr -m "trusted.pgfid.*" -de hex $B0/brick/dir1/file1 2>&1 | grep "trusted.pgfid" | cut -d'=' -f2`
+    TEST [ $HL = "0x00000001" ]
+
+    #rename file under same directory
+
+    TEST touch $M0/r_file1
+    PGFID_rfile1=`getfattr -m "trusted.pgfid.*" -de hex $B0/brick/r_file1 2>&1 | grep "trusted.pgfid"`
+
+    #cross check whether hard link count is one
+    HL=`getfattr -m "trusted.pgfid.*" -de hex $B0/brick/r_file1 2>&1 | grep "trusted.pgfid" | cut -d'=' -f2`
+
+    TEST [ $HL = "0x00000001" ]
+
+    #now rename the file to r_file1
+    TEST mv $M0/r_file1 $M0/r_file2
+
+    #now check the pgfid hard link count is still one or not
+    HL=`getfattr -m "trusted.pgfid.*" -de hex $B0/brick/r_file2 2>&1 | grep "trusted.pgfid" | cut -d'=' -f2` 
+
+    TEST [ $HL = "0x00000001" ]
+
+    #now move the file to a different directory where it has no hard link and check
+    TEST mkdir $M0/dir3;
+    TEST mv $M0/r_file2 $M0/dir3;
+
+    #now check the pgfid has changed or not and hard limit is one or not
+    PGFID_newDir=`getfattr -m "trusted.pgfid.*" -de hex $B0/brick/dir3/r_file2 2>&1 | grep "trusted.pgfid"`
+
+    #now the older pgfid and new pgfid shouldn't match
+    TEST [ $PGFID_rfile1 != $PGFID_newDir ]
+
+    HL=`getfattr -m "trusted.pgfid" -de hex $B0/brick/dir3/r_file2 2>&1 | grep "trusted.pgfid" | cut -d'=' -f2`
+    TEST [ $HL = "0x00000001" ]
+
+    TEST touch $M0/dir1/rl_file_1
+    ln $M0/dir1/rl_file_1 $M0/dir2/rl_file_2
+    mv $M0/dir1/rl_file_1 $M0/dir2
+
+    #now the there should be just one pgfid for both files
+    for i in $(seq 1 2); do
+            NL=`getfattr -m "trusted.pgfid" -de hex $B0/brick/dir2/rl_file_$i 2>&1 | grep "trusted.pgfid"|wc -l `
+            TEST_IN_LOOP [ $HL = "0x00000001" ]
+    done
+
+    #now pgfid of both files should match
+    P_rl_file_1=`getfattr -m "trusted.pgfid" -de hex $B0/brick/dir2/rl_file_1 2>&1 | grep "trusted.pgfid"`
+    P_rl_file_2=`getfattr -m "trusted.pgfid" -de hex $B0/brick/dir2/rl_file_2 2>&1 | grep "trusted.pgfid"`
+    TEST [ $P_rl_file_1 = $P_rl_file_2 ]
+
+    #now the no of hard link should be two for both rl_file_1 and rl_file_2
+    for i in  $(seq 1 2); do
+        HL=`getfattr -m "trusted.pgfid" -de hex $B0/brick/dir2/rl_file_$i 2>&1 | grep "trusted.pgfid" | cut -d'=' -f2`
+        TEST_IN_LOOP [ $HL = "0x00000002" ]
+    done
+
+    TEST rm -rf $M0/*
+}
+
+__init;
+links_in_same_directory;
+links_across_directories;
+
+cleanup