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[PATCH v4, 13/16] xfsprogs: metadump: move duplicate name handling into

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: [PATCH v4, 13/16] xfsprogs: metadump: move duplicate name handling into its own function
From: Alex Elder <aelder@xxxxxxx>
Date: Fri, 25 Feb 2011 12:13:48 -0600
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20110224021239.GA3166@dastard>
References: <201102182121.p1ILL2pI029171@xxxxxxxxxxxxxxxxxxxxxx> <20110224021239.GA3166@dastard>
Reply-to: aelder@xxxxxxx
Move the handling of duplicate names into its own function.  As a
result, all names other than "lost+found" files (not just those that
get obfuscated) will be checked to avoid duplication.

This makes the local buffer newname[] in generate_obfuscated_name()
unnecessary, so just drop it and use the passed-in name.

Signed-off-by: Alex Elder <aelder@xxxxxxx>

Updates:
- A comment about handling of a leading '/' character is now modified
  to match the updated code, rather than being deleted altogether.
- Renamed handle_duplicates() to be handle_duplicate_name().

---
 db/metadump.c |   78
++++++++++++++++++++++++++++++++++------------------------
 1 file changed, 47 insertions(+), 31 deletions(-)

Index: b/db/metadump.c
===================================================================
--- a/db/metadump.c
+++ b/db/metadump.c
@@ -552,6 +552,37 @@ obfuscate_name(
        ASSERT(libxfs_da_hashname(name, name_len) == hash);
 }
 
+/*
+ * Look up the given name in the name table.  If it is already
+ * present, find an alternate and attempt to use that name instead.
+ *
+ * Returns 1 if the (possibly modified) name is not present in the
+ * name table.  Returns 0 otherwise.
+ */
+static int
+handle_duplicate_name(xfs_dahash_t hash, size_t name_len, uchar_t
*name)
+{
+       int     dup = 0;
+
+       if (!nametable_find(hash, name_len, name))
+               return 1;       /* Not already in table */
+
+       /* Name is already in use.  Need to find an alternate. */
+
+       do {
+               obfuscate_name(hash, name_len, name);
+
+               /*
+                * Search the name table to be sure we don't produce
+                * a name that's already been used.
+                */
+               if (!nametable_find(hash, name_len, name))
+                       break;
+       } while (++dup < DUP_MAX);
+
+       return dup < DUP_MAX ? 1 : 0;
+}
+
 static void
 generate_obfuscated_name(
        xfs_ino_t               ino,
@@ -559,8 +590,6 @@ generate_obfuscated_name(
        uchar_t                 *name)
 {
        xfs_dahash_t            hash;
-       int                     dup = 0;
-       uchar_t                 newname[NAME_MAX];
 
        /*
         * We don't obfuscate "lost+found" or any orphan files
@@ -572,48 +601,35 @@ generate_obfuscated_name(
                return;
 
        /*
-        * If the name starts with a slash, just skip over it.  We
-        * will copy our obfuscated name back into space following
-        * the slash when we're done.  Our new name will not have
-        * the '/', and that's the version we'll keep in our
-        * duplicates table.  Note that the namelen value passed in
-        * does not include the leading slash (if any).
+        * If the name starts with a slash, just skip over it.  It
+        * isn't included in the hash and we don't record it in the
+        * name table.  Note that the namelen value passed in does
+        * not count the leading slash (if one is present).
         */
        if (*name == '/')
                name++;
 
-       hash = libxfs_da_hashname(name, namelen);
-       do {
-               obfuscate_name(hash, namelen, newname);
+       /* Obfuscate the name (if possible) */
 
-               /*
-                * Search the name table to be sure we don't produce
-                * a name that's already been used.
-                */
-               if (!nametable_find(hash, namelen, newname))
-                       break;
-       } while (++dup < DUP_MAX);
+       hash = libxfs_da_hashname(name, namelen);
+       obfuscate_name(hash, namelen, name);
 
        /*
-        * Update the caller's copy with the obfuscated name.
-        *
-        * If we couldn't come up with one, just use the original
-        * name without obfuscation.  Issue a warning if we managed
-        * to previously create an obfuscated name that matches the
-        * one we're working on now.
+        * Make sure the name is not something already seen.  If we
+        * fail to find a suitable alternate, we're dealing with a
+        * very pathological situation, and we may end up creating
+        * a duplicate name in the metadump, so issue a warning.
         */
-       if (dup < DUP_MAX)
-               memcpy(name, newname, namelen);
-       else if (nametable_find(hash, namelen, name))
+       if (!handle_duplicate_name(hash, namelen, name)) {
                print_warning("duplicate name for inode %llu "
                                "in dir inode %llu\n",
                        (unsigned long long) ino,
                        (unsigned long long) cur_ino);
+               return;
+       }
+
+       /* Create an entry for the new name in the name table. */
 
-       /*
-        * Create an entry for the name in the name table.  Use the
-        * original name if we got too many dups.
-        */
        if (!nametable_add(hash, namelen, name))
                print_warning("unable to record name for inode %llu "
                                "in dir inode %llu\n",


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