an ext2fs file system is mounted. The soft update changes added a check for B_DELWRI buffers. This exposed the complete brokenness of the previous quick fix for failing syncs (PR 3571, committed on 1997/08/04). Use a new buffer flag B_DIRTY and don't abuse B_DELWRI. B_DIRTY buffers are still written too late, as broken in the previous fix. This is fairly harmless, because B_DIRTY is only used for bitmap buffers and fsck.ext2 can fix up the bitmaps perfectly. Fixed a race in ULCK_BUF() (bremfree() was outside of the splbio() section).
by hacking on locked buffers without getblk()ing them, and we didn't even use splbio() to prevent biodone() changing the buffer underneath use when a write completes. I think there was no problem in practice on i386's because the operations on b_flags and numdirtybufs happen to be atomic. We still depend on biodone()'s operations on b_flags not interfering with ours. I think there is only interference for B_ERROR, and this is harmless because errors for async writes are ignored anyway. Don't use mark_buffer_dirty() except for superblock-related metadata. It was used in just one case where ordinary BSD buffering is more natural.
to not using splbio(), and has rotted a little. The races were probably harmless in practice because this function was only used for superblock updates, and separate superblock updates are probably prevented from running into each other by doing part of the update synchronously.
flushing of buffers in an attempt to reduce numdirtybuffers, and perhaps other problems.
keep ahold of buffers, and therefore leave filesystems dirty. I haven't been able to test, but the code compiles. Those who run -current, please test and report back!!! (Sorry :-)). PR: kern/3571 Submitted by: Dirk Keunecke <dk@panda.rhein-main.de>
cause a problem of spiraling death due to buffer resource limitations. The vfs_bio code in general had little ability to handle buffer resource management, and now it does. Also, there are a lot more knobs for tuning the vfs_bio code now. The knobs came free because of the need that there always be some immediately available buffers (non-delayed or locked) for use. Note that the buffer cache code is much less likely to get bogged down with lots of delayed writes, even more so than before.
Don't compile unused (debugging?) functions.
Included <sys/vnode.h> and its prerequisite <sys/proc.h>, and cleaned up includes. The vop_t changes made the non-inclusion of vnode.h fatal instead of just sloppy. i386_bitops.h: Changed `extern inline' to `static inline'. `extern inline' is a Linuxism that stops things from compiling without -O. Fixed idempotency identifier. Misc: Added prototypes. Staticized some functions so that prototypes are unnecessary. Added casts. Cleaned up includes.