clean up locking protocol in namei cache;

no longer `irele' when clearing cache after a `umount'.

SCCS-vsn: sys/kern/vfs_lookup.c 6.9
SCCS-vsn: sys/ufs/ffs/ufs_lookup.c 6.9
SCCS-vsn: sys/ufs/ufs/ufs_lookup.c 6.9

diff --git a/usr/src/sys/kern/vfs_lookup.c b/usr/src/sys/kern/vfs_lookup.c
index c04dcdf..3c3e1f1 100644 (file)
--- a/usr/src/sys/kern/vfs_lookup.c
+++ b/usr/src/sys/kern/vfs_lookup.c
@@ -1,4 +1,4 @@
-/*     vfs_lookup.c    6.8     84/07/02        */
+/*     vfs_lookup.c    6.9     84/07/02        */

 
 #include "../h/param.h"
 #include "../h/systm.h"
 
 #include "../h/param.h"
 #include "../h/systm.h"


@@ -212,6 +212,8 @@ dirloop2:
        }
        u.u_dent.d_namlen = i;
        u.u_dent.d_name[i] = 0;
        }
        u.u_dent.d_namlen = i;
        u.u_dent.d_name[i] = 0;

+       isdotdot = (i == 2 &&
+               u.u_dent.d_name[0] == '.' && u.u_dent.d_name[1] == '.');

 
        /*
         * Check for degenerate name (e.g. / or "")
 
        /*
         * Check for degenerate name (e.g. / or "")


@@ -255,11 +257,11 @@ dirloop2:
                        nchstats.ncs_miss++;
                        ncp = NULL;
                } else {
                        nchstats.ncs_miss++;
                        ncp = NULL;
                } else {

-                       if (ncp->nc_id != ncp->nc_ip->i_id)
+                       if (ncp->nc_id != ncp->nc_ip->i_id) {

                                nchstats.ncs_falsehits++;
                                nchstats.ncs_falsehits++;

-                       else if (*cp == '/' || docache) {
-
-                               nchstats.ncs_goodhits++;
+                       } else if (*cp == '\0' && !docache) {
+                               nchstats.ncs_badhits++;
+                       } else {

 
                                        /*
                                         * move this slot to end of LRU
 
                                        /*
                                         * move this slot to end of LRU


@@ -277,6 +279,11 @@ dirloop2:
                                        nchtail = &ncp->nc_nxt;
                                }
 
                                        nchtail = &ncp->nc_nxt;
                                }
 

+                               /*
+                                * Get the next inode in the path.
+                                * See comment above other `iunlock' code for
+                                * an explaination of the locking protocol.
+                                */

                                pdp = dp;
                                dp = ncp->nc_ip;
                                if (dp == NULL)
                                pdp = dp;
                                dp = ncp->nc_ip;
                                if (dp == NULL)


@@ -285,19 +292,40 @@ dirloop2:
                                        dp->i_count++;
                                else if (dp->i_count) {
                                        dp->i_count++;
                                        dp->i_count++;
                                else if (dp->i_count) {
                                        dp->i_count++;

-                                       ilock(dp);
-                                       iunlock(pdp);
+                                       if (isdotdot) {
+                                               iunlock(pdp);
+                                               ilock(dp);
+                                       } else {
+                                               ilock(dp);
+                                               iunlock(pdp);
+                                       }

                                } else {
                                } else {

-                                       igrab(dp);
-                                       iunlock(pdp);
+                                       if (isdotdot) {
+                                               iunlock(pdp);
+                                               igrab(dp);
+                                       } else {
+                                               igrab(dp);
+                                               iunlock(pdp);
+                                       }

                                }
 
                                }
 

-                               u.u_dent.d_ino = dp->i_number;
-                               /* u_dent.d_reclen is garbage ... */
-
-                               goto haveino;
-                       } else
-                               nchstats.ncs_badhits++;
+                               /*
+                                * Verify that the inode that we got
+                                * did not change while we were waiting
+                                * for it to be locked.
+                                */
+                               if (ncp->nc_id != ncp->nc_ip->i_id) {
+                                       iput(dp);
+                                       ilock(pdp);
+                                       dp = pdp;
+                                       nchstats.ncs_falsehits++;
+                               } else {
+                                       u.u_dent.d_ino = dp->i_number;
+                                       /* u_dent.d_reclen is garbage ... */
+                                       nchstats.ncs_goodhits++;
+                                       goto haveino;
+                               }
+                       }

 
                        /*
                         * Last component and we are renaming or deleting,
 
                        /*
                         * Last component and we are renaming or deleting,


@@ -602,9 +630,7 @@ found:
         * file system: indirect .. in root inode to reevaluate
         * in directory file system was mounted on.
         */
         * file system: indirect .. in root inode to reevaluate
         * in directory file system was mounted on.
         */

-       isdotdot = 0;
-       if (bcmp(u.u_dent.d_name, "..", 3) == 0) {
-               isdotdot++;
+       if (isdotdot) {

                if (dp == u.u_rdir)
                        u.u_dent.d_ino = dp->i_number;
                else if (u.u_dent.d_ino == ROOTINO &&
                if (dp == u.u_rdir)
                        u.u_dent.d_ino = dp->i_number;
                else if (u.u_dent.d_ino == ROOTINO &&


@@ -1103,7 +1129,8 @@ checkpath(source, target)
                if (error != 0)
                        break;
                if (dirbuf.dotdot_namlen != 2 ||
                if (error != 0)
                        break;
                if (dirbuf.dotdot_namlen != 2 ||

-                   bcmp(dirbuf.dotdot_name, "..", 3) != 0) {
+                   dirbuf.dotdot_name[0] != '.' ||
+                   dirbuf.dotdot_name[1] != '.') {

                        error = ENOTDIR;
                        break;
                }
                        error = ENOTDIR;
                        break;
                }


@@ -1178,9 +1205,13 @@ nchinval(dev)
                    (ncp->nc_idev != dev && ncp->nc_dev != dev))
                        continue;
 
                    (ncp->nc_idev != dev && ncp->nc_dev != dev))
                        continue;
 

+                       /* free the resources we had */

                ncp->nc_idev = NODEV;
                ncp->nc_dev = NODEV;
                ncp->nc_idev = NODEV;
                ncp->nc_dev = NODEV;

+               ncp->nc_id = NULL;

                ncp->nc_ino = 0;
                ncp->nc_ino = 0;

+               ncp->nc_ip = NULL;
+

 
                        /* remove the entry from its hash chain */
                remque(ncp);
 
                        /* remove the entry from its hash chain */
                remque(ncp);


@@ -1195,10 +1226,6 @@ nchinval(dev)
                else
                        nchtail = ncp->nc_prev;
 
                else
                        nchtail = ncp->nc_prev;
 

-                       /* free the inode we had */
-               irele(ncp->nc_ip);
-               ncp->nc_ip = NULL;
-

                        /* cause rescan of list, it may have altered */
                nxtcp = nchhead;
                        /* put the now-free entry at head of LRU */
                        /* cause rescan of list, it may have altered */
                nxtcp = nchhead;
                        /* put the now-free entry at head of LRU */

diff --git a/usr/src/sys/ufs/ffs/ufs_lookup.c b/usr/src/sys/ufs/ffs/ufs_lookup.c
index 5742c7a..83b8798 100644 (file)
--- a/usr/src/sys/ufs/ffs/ufs_lookup.c
+++ b/usr/src/sys/ufs/ffs/ufs_lookup.c
@@ -1,4 +1,4 @@
-/*     ufs_lookup.c    6.8     84/07/02        */
+/*     ufs_lookup.c    6.9     84/07/02        */

 
 #include "../h/param.h"
 #include "../h/systm.h"
 
 #include "../h/param.h"
 #include "../h/systm.h"


@@ -212,6 +212,8 @@ dirloop2:
        }
        u.u_dent.d_namlen = i;
        u.u_dent.d_name[i] = 0;
        }
        u.u_dent.d_namlen = i;
        u.u_dent.d_name[i] = 0;

+       isdotdot = (i == 2 &&
+               u.u_dent.d_name[0] == '.' && u.u_dent.d_name[1] == '.');

 
        /*
         * Check for degenerate name (e.g. / or "")
 
        /*
         * Check for degenerate name (e.g. / or "")


@@ -255,11 +257,11 @@ dirloop2:
                        nchstats.ncs_miss++;
                        ncp = NULL;
                } else {
                        nchstats.ncs_miss++;
                        ncp = NULL;
                } else {

-                       if (ncp->nc_id != ncp->nc_ip->i_id)
+                       if (ncp->nc_id != ncp->nc_ip->i_id) {

                                nchstats.ncs_falsehits++;
                                nchstats.ncs_falsehits++;

-                       else if (*cp == '/' || docache) {
-
-                               nchstats.ncs_goodhits++;
+                       } else if (*cp == '\0' && !docache) {
+                               nchstats.ncs_badhits++;
+                       } else {

 
                                        /*
                                         * move this slot to end of LRU
 
                                        /*
                                         * move this slot to end of LRU


@@ -277,6 +279,11 @@ dirloop2:
                                        nchtail = &ncp->nc_nxt;
                                }
 
                                        nchtail = &ncp->nc_nxt;
                                }
 

+                               /*
+                                * Get the next inode in the path.
+                                * See comment above other `iunlock' code for
+                                * an explaination of the locking protocol.
+                                */

                                pdp = dp;
                                dp = ncp->nc_ip;
                                if (dp == NULL)
                                pdp = dp;
                                dp = ncp->nc_ip;
                                if (dp == NULL)


@@ -285,19 +292,40 @@ dirloop2:
                                        dp->i_count++;
                                else if (dp->i_count) {
                                        dp->i_count++;
                                        dp->i_count++;
                                else if (dp->i_count) {
                                        dp->i_count++;

-                                       ilock(dp);
-                                       iunlock(pdp);
+                                       if (isdotdot) {
+                                               iunlock(pdp);
+                                               ilock(dp);
+                                       } else {
+                                               ilock(dp);
+                                               iunlock(pdp);
+                                       }

                                } else {
                                } else {

-                                       igrab(dp);
-                                       iunlock(pdp);
+                                       if (isdotdot) {
+                                               iunlock(pdp);
+                                               igrab(dp);
+                                       } else {
+                                               igrab(dp);
+                                               iunlock(pdp);
+                                       }

                                }
 
                                }
 

-                               u.u_dent.d_ino = dp->i_number;
-                               /* u_dent.d_reclen is garbage ... */
-
-                               goto haveino;
-                       } else
-                               nchstats.ncs_badhits++;
+                               /*
+                                * Verify that the inode that we got
+                                * did not change while we were waiting
+                                * for it to be locked.
+                                */
+                               if (ncp->nc_id != ncp->nc_ip->i_id) {
+                                       iput(dp);
+                                       ilock(pdp);
+                                       dp = pdp;
+                                       nchstats.ncs_falsehits++;
+                               } else {
+                                       u.u_dent.d_ino = dp->i_number;
+                                       /* u_dent.d_reclen is garbage ... */
+                                       nchstats.ncs_goodhits++;
+                                       goto haveino;
+                               }
+                       }

 
                        /*
                         * Last component and we are renaming or deleting,
 
                        /*
                         * Last component and we are renaming or deleting,


@@ -602,9 +630,7 @@ found:
         * file system: indirect .. in root inode to reevaluate
         * in directory file system was mounted on.
         */
         * file system: indirect .. in root inode to reevaluate
         * in directory file system was mounted on.
         */

-       isdotdot = 0;
-       if (bcmp(u.u_dent.d_name, "..", 3) == 0) {
-               isdotdot++;
+       if (isdotdot) {

                if (dp == u.u_rdir)
                        u.u_dent.d_ino = dp->i_number;
                else if (u.u_dent.d_ino == ROOTINO &&
                if (dp == u.u_rdir)
                        u.u_dent.d_ino = dp->i_number;
                else if (u.u_dent.d_ino == ROOTINO &&


@@ -1103,7 +1129,8 @@ checkpath(source, target)
                if (error != 0)
                        break;
                if (dirbuf.dotdot_namlen != 2 ||
                if (error != 0)
                        break;
                if (dirbuf.dotdot_namlen != 2 ||

-                   bcmp(dirbuf.dotdot_name, "..", 3) != 0) {
+                   dirbuf.dotdot_name[0] != '.' ||
+                   dirbuf.dotdot_name[1] != '.') {

                        error = ENOTDIR;
                        break;
                }
                        error = ENOTDIR;
                        break;
                }


@@ -1178,9 +1205,13 @@ nchinval(dev)
                    (ncp->nc_idev != dev && ncp->nc_dev != dev))
                        continue;
 
                    (ncp->nc_idev != dev && ncp->nc_dev != dev))
                        continue;
 

+                       /* free the resources we had */

                ncp->nc_idev = NODEV;
                ncp->nc_dev = NODEV;
                ncp->nc_idev = NODEV;
                ncp->nc_dev = NODEV;

+               ncp->nc_id = NULL;

                ncp->nc_ino = 0;
                ncp->nc_ino = 0;

+               ncp->nc_ip = NULL;
+

 
                        /* remove the entry from its hash chain */
                remque(ncp);
 
                        /* remove the entry from its hash chain */
                remque(ncp);


@@ -1195,10 +1226,6 @@ nchinval(dev)
                else
                        nchtail = ncp->nc_prev;
 
                else
                        nchtail = ncp->nc_prev;
 

-                       /* free the inode we had */
-               irele(ncp->nc_ip);
-               ncp->nc_ip = NULL;
-

                        /* cause rescan of list, it may have altered */
                nxtcp = nchhead;
                        /* put the now-free entry at head of LRU */
                        /* cause rescan of list, it may have altered */
                nxtcp = nchhead;
                        /* put the now-free entry at head of LRU */

diff --git a/usr/src/sys/ufs/ufs/ufs_lookup.c b/usr/src/sys/ufs/ufs/ufs_lookup.c
index 5742c7a..83b8798 100644 (file)
--- a/usr/src/sys/ufs/ufs/ufs_lookup.c
+++ b/usr/src/sys/ufs/ufs/ufs_lookup.c
@@ -1,4 +1,4 @@
-/*     ufs_lookup.c    6.8     84/07/02        */
+/*     ufs_lookup.c    6.9     84/07/02        */

 
 #include "../h/param.h"
 #include "../h/systm.h"
 
 #include "../h/param.h"
 #include "../h/systm.h"


@@ -212,6 +212,8 @@ dirloop2:
        }
        u.u_dent.d_namlen = i;
        u.u_dent.d_name[i] = 0;
        }
        u.u_dent.d_namlen = i;
        u.u_dent.d_name[i] = 0;

+       isdotdot = (i == 2 &&
+               u.u_dent.d_name[0] == '.' && u.u_dent.d_name[1] == '.');

 
        /*
         * Check for degenerate name (e.g. / or "")
 
        /*
         * Check for degenerate name (e.g. / or "")


@@ -255,11 +257,11 @@ dirloop2:
                        nchstats.ncs_miss++;
                        ncp = NULL;
                } else {
                        nchstats.ncs_miss++;
                        ncp = NULL;
                } else {

-                       if (ncp->nc_id != ncp->nc_ip->i_id)
+                       if (ncp->nc_id != ncp->nc_ip->i_id) {

                                nchstats.ncs_falsehits++;
                                nchstats.ncs_falsehits++;

-                       else if (*cp == '/' || docache) {
-
-                               nchstats.ncs_goodhits++;
+                       } else if (*cp == '\0' && !docache) {
+                               nchstats.ncs_badhits++;
+                       } else {

 
                                        /*
                                         * move this slot to end of LRU
 
                                        /*
                                         * move this slot to end of LRU


@@ -277,6 +279,11 @@ dirloop2:
                                        nchtail = &ncp->nc_nxt;
                                }
 
                                        nchtail = &ncp->nc_nxt;
                                }
 

+                               /*
+                                * Get the next inode in the path.
+                                * See comment above other `iunlock' code for
+                                * an explaination of the locking protocol.
+                                */

                                pdp = dp;
                                dp = ncp->nc_ip;
                                if (dp == NULL)
                                pdp = dp;
                                dp = ncp->nc_ip;
                                if (dp == NULL)


@@ -285,19 +292,40 @@ dirloop2:
                                        dp->i_count++;
                                else if (dp->i_count) {
                                        dp->i_count++;
                                        dp->i_count++;
                                else if (dp->i_count) {
                                        dp->i_count++;

-                                       ilock(dp);
-                                       iunlock(pdp);
+                                       if (isdotdot) {
+                                               iunlock(pdp);
+                                               ilock(dp);
+                                       } else {
+                                               ilock(dp);
+                                               iunlock(pdp);
+                                       }

                                } else {
                                } else {

-                                       igrab(dp);
-                                       iunlock(pdp);
+                                       if (isdotdot) {
+                                               iunlock(pdp);
+                                               igrab(dp);
+                                       } else {
+                                               igrab(dp);
+                                               iunlock(pdp);
+                                       }

                                }
 
                                }
 

-                               u.u_dent.d_ino = dp->i_number;
-                               /* u_dent.d_reclen is garbage ... */
-
-                               goto haveino;
-                       } else
-                               nchstats.ncs_badhits++;
+                               /*
+                                * Verify that the inode that we got
+                                * did not change while we were waiting
+                                * for it to be locked.
+                                */
+                               if (ncp->nc_id != ncp->nc_ip->i_id) {
+                                       iput(dp);
+                                       ilock(pdp);
+                                       dp = pdp;
+                                       nchstats.ncs_falsehits++;
+                               } else {
+                                       u.u_dent.d_ino = dp->i_number;
+                                       /* u_dent.d_reclen is garbage ... */
+                                       nchstats.ncs_goodhits++;
+                                       goto haveino;
+                               }
+                       }

 
                        /*
                         * Last component and we are renaming or deleting,
 
                        /*
                         * Last component and we are renaming or deleting,


@@ -602,9 +630,7 @@ found:
         * file system: indirect .. in root inode to reevaluate
         * in directory file system was mounted on.
         */
         * file system: indirect .. in root inode to reevaluate
         * in directory file system was mounted on.
         */

-       isdotdot = 0;
-       if (bcmp(u.u_dent.d_name, "..", 3) == 0) {
-               isdotdot++;
+       if (isdotdot) {

                if (dp == u.u_rdir)
                        u.u_dent.d_ino = dp->i_number;
                else if (u.u_dent.d_ino == ROOTINO &&
                if (dp == u.u_rdir)
                        u.u_dent.d_ino = dp->i_number;
                else if (u.u_dent.d_ino == ROOTINO &&


@@ -1103,7 +1129,8 @@ checkpath(source, target)
                if (error != 0)
                        break;
                if (dirbuf.dotdot_namlen != 2 ||
                if (error != 0)
                        break;
                if (dirbuf.dotdot_namlen != 2 ||

-                   bcmp(dirbuf.dotdot_name, "..", 3) != 0) {
+                   dirbuf.dotdot_name[0] != '.' ||
+                   dirbuf.dotdot_name[1] != '.') {

                        error = ENOTDIR;
                        break;
                }
                        error = ENOTDIR;
                        break;
                }


@@ -1178,9 +1205,13 @@ nchinval(dev)
                    (ncp->nc_idev != dev && ncp->nc_dev != dev))
                        continue;
 
                    (ncp->nc_idev != dev && ncp->nc_dev != dev))
                        continue;
 

+                       /* free the resources we had */

                ncp->nc_idev = NODEV;
                ncp->nc_dev = NODEV;
                ncp->nc_idev = NODEV;
                ncp->nc_dev = NODEV;

+               ncp->nc_id = NULL;

                ncp->nc_ino = 0;
                ncp->nc_ino = 0;

+               ncp->nc_ip = NULL;
+

 
                        /* remove the entry from its hash chain */
                remque(ncp);
 
                        /* remove the entry from its hash chain */
                remque(ncp);


@@ -1195,10 +1226,6 @@ nchinval(dev)
                else
                        nchtail = ncp->nc_prev;
 
                else
                        nchtail = ncp->nc_prev;
 

-                       /* free the inode we had */
-               irele(ncp->nc_ip);
-               ncp->nc_ip = NULL;
-

                        /* cause rescan of list, it may have altered */
                nxtcp = nchhead;
                        /* put the now-free entry at head of LRU */
                        /* cause rescan of list, it may have altered */
                nxtcp = nchhead;
                        /* put the now-free entry at head of LRU */