diff options
Diffstat (limited to 'contrib/sys/softupdates/softdep.h')
-rw-r--r-- | contrib/sys/softupdates/softdep.h | 49 |
1 files changed, 32 insertions, 17 deletions
diff --git a/contrib/sys/softupdates/softdep.h b/contrib/sys/softupdates/softdep.h index 6b5d416..3435f63 100644 --- a/contrib/sys/softupdates/softdep.h +++ b/contrib/sys/softupdates/softdep.h @@ -52,7 +52,7 @@ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * - * from: @(#)softdep.h 9.4 (McKusick) 1/15/98 + * @(#)softdep.h 9.5 (McKusick) 2/11/98 */ #include <sys/queue.h> @@ -201,31 +201,45 @@ struct pagedep { /* * The "inodedep" structure tracks the set of dependencies associated - * with an inode. Each block that is allocated is represented by an + * with an inode. One task that it must manage is delayed operations + * (i.e., work requests that must be held until the inodedep's associated + * inode has been written to disk). Getting an inode from its incore + * state to the disk requires two steps to be taken by the filesystem + * in this order: first the inode must be copied to its disk buffer by + * the VOP_UPDATE operation; second the inode's buffer must be written + * to disk. To ensure that both operations have happened in the required + * order, the inodedep maintains two lists. Delayed operations are + * placed on the id_inowait list. When the VOP_UPDATE is done, all + * operations on the id_inowait list are moved to the id_bufwait list. + * When the buffer is written, the items on the id_bufwait list can be + * safely moved to the work queue to be processed. A second task of the + * inodedep structure is to track the status of block allocation within + * the inode. Each block that is allocated is represented by an * "allocdirect" structure (see below). It is linked onto the id_newinoupdt * list until both its contents and its allocation in the cylinder - * group map have been written to disk. Once the dependencies have been + * group map have been written to disk. Once these dependencies have been * satisfied, it is removed from the id_newinoupdt list and any followup * actions such as releasing the previous block or fragment are placed - * on the id_inowait list. When an inode is updated (copied from the - * in-core inode structure to a disk buffer containing its on-disk - * copy), the "inodedep" structure is linked onto the buffer through - * its worklist. Thus it will be notified when the buffer is about + * on the id_inowait list. When an inode is updated (a VOP_UPDATE is + * done), the "inodedep" structure is linked onto the buffer through + * its worklist. Thus, it will be notified when the buffer is about * to be written and when it is done. At the update time, all the * elements on the id_newinoupdt list are moved to the id_inoupdt list * since those changes are now relevant to the copy of the inode in the - * buffer. When the buffer containing the inode is written to disk, any - * updates listed on the id_inoupdt list are rolled back as they are - * not yet safe. Following the write, the changes are once again rolled - * forward and any actions on the id_inowait list are processed (since - * the previously allocated blocks are no longer claimed on the disk). + * buffer. Also at update time, the tasks on the id_inowait list are + * moved to the id_bufwait list so that they will be executed when + * the updated inode has been written to disk. When the buffer containing + * the inode is written to disk, any updates listed on the id_inoupdt + * list are rolled back as they are not yet safe. Following the write, + * the changes are once again rolled forward and any actions on the + * id_bufwait list are processed (since those actions are now safe). * The entries on the id_inoupdt and id_newinoupdt lists must be kept * sorted by logical block number to speed the calculation of the size * of the rolled back inode (see explanation in initiate_write_inodeblock). * When a directory entry is created, it is represented by a diradd. - * The diradd is added to the id_inowait list and is not permitted to be - * written to disk until the inode that it represents is written. After - * the inode is written, the id_inowait list is processed and the diradd + * The diradd is added to the id_inowait list as it cannot be safely + * written to disk until the inode that it represents is on disk. After + * the inode is written, the id_bufwait list is processed and the diradd * entries are moved to the id_pendinghd list where they remain until * the directory block containing the name has been written to disk. * The purpose of keeping the entries on the id_pendinghd list is so that @@ -244,7 +258,8 @@ struct inodedep { struct buf *id_buf; /* related bmsafemap (if pending) */ off_t id_savedsize; /* file size saved during rollback */ struct workhead id_pendinghd; /* entries awaiting directory write */ - struct workhead id_inowait; /* operations after inode written */ + struct workhead id_bufwait; /* operations after inode written */ + struct workhead id_inowait; /* operations waiting inode update */ struct allocdirectlst id_inoupdt; /* updates before inode written */ struct allocdirectlst id_newinoupdt; /* updates when inode written */ }; @@ -460,7 +475,7 @@ struct freefile { * if appropriate and is never cleared. */ struct diradd { - struct worklist da_list; /* id_inowait and id_pendinghd list */ + struct worklist da_list; /* id_inowait or id_pendinghd list */ # define da_state da_list.wk_state /* state of the new directory entry */ LIST_ENTRY(diradd) da_pdlist; /* pagedep holding directory block */ doff_t da_offset; /* offset of new dir entry in dir blk */ |