diff options
| -rw-r--r-- | libdiskfs/dir-lookup.c | 199 |
1 files changed, 115 insertions, 84 deletions
diff --git a/libdiskfs/dir-lookup.c b/libdiskfs/dir-lookup.c index 97e6e2a2..56b6580e 100644 --- a/libdiskfs/dir-lookup.c +++ b/libdiskfs/dir-lookup.c @@ -163,110 +163,141 @@ diskfs_S_dir_lookup (struct protid *dircred, /* If this is translated, start the translator (if necessary) and return. */ - repeat_transcheck: - if ((diskfs_node_translated (np) - || np->translator.control != MACH_PORT_NULL) - && !((flags & O_NOTRANS) && lastcomp)) + if (!lastcomp || !(flags & O_NOTRANS)) { - mach_port_t control = np->translator.control; - uid_t *uids, *gids; + mach_port_t control; + uid_t *uids = 0, *gids; int nuids, ngids; - file_t dirfile; - - dirfile = (ports_get_right - (diskfs_make_protid - (diskfs_make_peropen (dnp, 0, - dircred->po->dotdotport), - 0, 0, 0, 0))); - mach_port_insert_right (mach_task_self (), dirfile, dirfile, - MACH_MSG_TYPE_MAKE_SEND); - mach_port_mod_refs (mach_task_self (), dirfile, - MACH_PORT_RIGHT_SEND, 1); - - if (control == MACH_PORT_NULL) - { - mutex_unlock (&dnp->lock); - error = diskfs_start_translator (np, dirfile, dircred); - if (error) - { - mach_port_deallocate (mach_task_self (), dirfile); - diskfs_nrele (dnp); - dnp = 0; - goto out; - } - control = np->translator.control; - } - else - mutex_unlock (&dnp->lock); + file_t dirfile = MACH_PORT_NULL; - uids = dircred->uids; - gids = dircred->gids; - nuids = dircred->nuids; - ngids = dircred->ngids; + /* Be very careful not to hold an inode lock while fetching + a translator lock and vice versa. */ - /* Acquire a reference because someone could - blow away np->translator once we release the lock. */ - mach_port_mod_refs (mach_task_self (), control, - MACH_PORT_RIGHT_SEND, 1); + /* Our code depends heavily on these being different. + This case can't happen in real life, so we're fine. */ + if (np == dnp) + { + error = ED; + goto out; + } mutex_unlock (&np->lock); - - /* We turn off O_NOLINK here if this is not the last - component because fsys_getroot always thinks it's the - last node. */ - error = fsys_getroot (control, dirfile, MACH_MSG_TYPE_MOVE_SEND, - uids, nuids, gids, ngids, - lastcomp ? flags : flags & ~O_NOLINK, - retry, retryname, returned_port); - mach_port_deallocate (mach_task_self (), dirfile); - if (error == MACH_SEND_INVALID_DEST) + mutex_unlock (&dnp->lock); + + repeat_trans: + mutex_lock (&np->translator.lock); + if (np->translator.control != MACH_PORT_NULL) { - /* The server has died. Deallocate our right and - go back. */ - /* Make sure we honor the locking hierarchy here. */ - if (strcmp (path, "..")) + control = np->translator.control; + mach_port_mod_refs (mach_task_self (), control, + MACH_PORT_RIGHT_SEND, 1); + mutex_unlock (&np->translator.lock); + + /* Now we have a copy of the translator port that isn't + dependent on the translator lock itself. Relock + the directory, make a port from it, and then call + fsys_getroot. */ + + if (dirfile == MACH_PORT_NULL) { mutex_lock (&dnp->lock); - mutex_lock (&np->lock); + dirfile = (ports_get_right + (diskfs_make_protid + (diskfs_make_peropen (dnp, 0, + dircred->po->dotdotport), + 0, 0, 0, 0))); + mach_port_insert_right (mach_task_self (), dirfile, dirfile, + MACH_MSG_TYPE_MAKE_SEND); + mutex_unlock (&dnp->lock); } - else + + if (!uids) { - mutex_lock (&np->lock); - mutex_lock (&dnp->lock); + uids = dircred->uids; + gids = dircred->gids; + nuids = dircred->nuids; + ngids = dircred->ngids; } + + /* We turn off O_NOLINK here if this is not the last + component because fsys_getroot always thinks it's the + last node. */ + error = fsys_getroot (control, dirfile, MACH_MSG_TYPE_COPY_SEND, + uids, nuids, gids, ngids, + lastcomp ? flags : flags & ~O_NOLINK, + retry, retryname, returned_port); + + /* If we got MACH_SEND_INVALID_DEST, then the server is dead. + Zero out the old control port and try everything again. */ - /* Make sure nobody's set it while we were away */ - if (np->translator.control == control) - /* Clear it */ - fshelp_translator_drop (&np->translator); + if (error == MACH_SEND_INVALID_DEST) + { + mutex_lock (&np->translator.lock); - /* The reference that we created above. */ - mach_port_deallocate (mach_task_self (), control); + /* Only zero it if it hasn't changed. */ - error = 0; + if (np->translator.control == control) + fshelp_translator_drop (&np->translator); + mutex_unlock (&np->translator.lock); + + /* And we're done with this port. */ + mach_port_deallocate (mach_task_self (), control); - goto repeat_transcheck; + goto repeat_trans; + } + + /* Otherwise, we're done; return to the user. If there + are more components after this name, be sure to append + them to the user's retry path. */ + if (!error && !lastcomp) + { + strcat (retryname, "/"); + strcat (retryname, nextname); + } + diskfs_nrele (dnp); + diskfs_nrele (np); + mach_port_deallocate (mach_task_self (), dirfile); + return error; } - /* The reference that we created above. */ - mach_port_deallocate (mach_task_self (), control); - diskfs_nrele (dnp); - diskfs_nrele (np); - np = 0; - dnp = 0; - - if (*returned_port != MACH_PORT_NULL) - *returned_port_poly = MACH_MSG_TYPE_MOVE_SEND; else - *returned_port_poly = MACH_MSG_TYPE_COPY_SEND; - - /* If there are more components after this one, - arrange to have a correct repeat call made. */ - if (!error && !lastcomp) { - strcat (retryname, "/"); - strcat (retryname, nextname); + /* If we get here, then we have no control port. + Check to see if there is a passive translator, and if so + repeat the translator check. */ + mutex_unlock (&np->translator.lock); + + mutex_lock (&np->lock); + if (diskfs_node_translated (np)) + { + /* Start the translator. */ + if (dirfile == MACH_PORT_NULL) + { + /* This code is the same as above. */ + mutex_unlock (&np->lock); + mutex_lock (&dnp->lock); + dirfile = (ports_get_right + (diskfs_make_protid + (diskfs_make_peropen (dnp, 0, + dircred->po + ->dotdotport), + 0, 0, 0, 0))); + mach_port_insert_right (mach_task_self (), dirfile, + dirfile, + MACH_MSG_TYPE_MAKE_SEND); + mutex_unlock (&dnp->lock); + mutex_lock (&np->lock); + } + error = diskfs_start_translator (np, dirfile, dircred); + if (error) + { + mach_port_deallocate (mach_task_self (), dirfile); + diskfs_nrele (dnp); + diskfs_nput (np); + return error; + } + goto repeat_trans; + } } - goto out; } if (S_ISLNK (np->dn_stat.st_mode) |