- Don't defeat the FIFO nature of the buffer cache by eliminating the
most recently used buffer when we are under paging pressure. This is
a perversion of the buffer and page replacement algor

- Don't defeat the FIFO nature of the buffer cache by eliminating the
most recently used buffer when we are under paging pressure. This is
a perversion of the buffer and page replacement algorithms and recent
improvements to the page daemon have rendered it unnecessary. In the
event that low-memory deadlocks become an issue it would be possible
to make a daemon or event handler that performs a similar action on
the oldest buffers rather than the newest. Since the buf cache
is analogous to the page cache and some minimum working set is desired
another possibility is to simply shrink the minimum working set which
has less downside now that file pages are not directly mapped.

Sponsored by: EMC / Isilon
Reviewed by: alc, kib (with some minor objection)
Tested by: pho

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Merge ^/head r285341 through r285792.

Do not allow creation of the dirty buffers for the dead buffer
objects, i.e. for buffer objects which vnode was reclaimed. Buffer
cache cannot write such buffers. Return the error and discard the
b

Do not allow creation of the dirty buffers for the dead buffer
objects, i.e. for buffer objects which vnode was reclaimed. Buffer
cache cannot write such buffers. Return the error and discard the
buffer immediately on write attempt.

BO_DIRTY now always set during vnode reclamation, since it is used not
only for the INVARIANTS checks. Do allow placement of the clean
buffers on dead bufobj list, otherwise filesystems cannot use bufcache
at all after the devvp reclaim.

Reported and tested by: trasz
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

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Merge ^/head r284737 through r285152.

Handle errors from background write of the cylinder group blocks.

First, on the write error, bufdone() call from ffs_backgroundwrite()
panics because pbrelvp() cleared bp->b_bufobj, while brelse() w

Handle errors from background write of the cylinder group blocks.

First, on the write error, bufdone() call from ffs_backgroundwrite()
panics because pbrelvp() cleared bp->b_bufobj, while brelse() would
try to re-dirty the copy of the cg buffer. Handle this by setting
B_INVAL for the case of BIO_ERROR.

Second, we must re-dirty the real buffer containing the cylinder group
block data when background write failed. Real cg buffer was already
marked clean in ffs_bufwrite(). After the BV_BKGRDINPROG flag is
cleared on the real cg buffer in ffs_backgroundwrite(), buffer scan
may reuse the buffer at any moment. The result is lost write, and if
the write error was only transient, we get corrupted bitmaps.

We cannot re-dirty the original cg buffer in the
ffs_backgroundwritedone(), since the context is not sleepable,
preventing us from sleeping for origbp' lock. Add BV_BKGDERR flag
(protected by the buffer object lock), which is converted into delayed
write by brelse(), bqrelse() and buffer scan.

In collaboration with: Conrad Meyer <cse.cem@gmail.com>
Reviewed by: mckusick
Sponsored by: The FreeBSD Foundation (kib),
EMC/Isilon storage division (Conrad)
MFC after: 2 weeks

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Merge ^/head r284644 through r284736.

Only take previous buffer queue lock (olock) when needed for REMFREE
in binsfree().

Submitted by: Conrad Meyer
Sponsored by: EMC / Isilon Storage Division
Review: https://reviews.freebsd.org/D2882
M

Only take previous buffer queue lock (olock) when needed for REMFREE
in binsfree().

Submitted by: Conrad Meyer
Sponsored by: EMC / Isilon Storage Division
Review: https://reviews.freebsd.org/D2882
MFC after: 1 week

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Catch up with HEAD (r280229-r284686).

Merge sync of head

Merge from head

MFH: r281855-r282312

Sponsored by: The FreeBSD Foundation

Partially revert r255986: do not call VOP_FSYNC() when helping
bufdaemon in getnewbuf(), do use buf_flush(). The difference is that
bufdaemon uses TRYLOCK to get buffer locks, which allows calls to

Partially revert r255986: do not call VOP_FSYNC() when helping
bufdaemon in getnewbuf(), do use buf_flush(). The difference is that
bufdaemon uses TRYLOCK to get buffer locks, which allows calls to
getnewbuf() while another buffer is locked.

Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

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MAXBSIZE defines both the largest UFS block size and the
largest size for a buffer in the buffer cache. This patch
defines a new constant MAXBCACHEBUF, which is the largest
size for a buffer in the b

MAXBSIZE defines both the largest UFS block size and the
largest size for a buffer in the buffer cache. This patch
defines a new constant MAXBCACHEBUF, which is the largest
size for a buffer in the buffer cache. Having a separate
constant allows MAXBCACHEBUF to be set larger than MAXBSIZE
on a per-architecture basis, so that NFS can do larger read/writes
for these architectures. It modifies sys/param.h so that BKVASIZE
can also be set on a per-architecture basis.
A couple of cases where NFS used MAXBSIZE instead of NFS_MAXBSIZE
is fixed as well.

Differential Revision: https://reviews.freebsd.org/D2330
Reviewed by: mav, kib
MFC after: 2 weeks

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MFH: r278968-r280640

Sponsored by: The FreeBSD Foundation

Merge r278538 through r280226.

Merge from head

Reset bp->bio_done to unmapped_buf when removing a transient map in biodone.

Submitted by: Scott Ferris <scott.ferris@isilon.com>
Sponsored by: EMC / Isilon Storage Division
Reviewed by: kib

Reintegrate head: r274132-r277384

Sponsored by: The FreeBSD Foundation

Reintegrate head revisions r273096-r277147

Sponsored by: The FreeBSD Foundation

MFhead @ r275663

Merge ^/head r275478 through r275622.

When getnewbuf_reuse_bp() is called to reclaim some (clean) buffer,
the vnode owning the buffer is not locked. More, it cannot be locked
safely, since getnewbuf_reuse_bp() is called from newbuf(), a

When getnewbuf_reuse_bp() is called to reclaim some (clean) buffer,
the vnode owning the buffer is not locked. More, it cannot be locked
safely, since getnewbuf_reuse_bp() is called from newbuf(), and some
other vnode is already locked, for which reused buffer will be
reassigned.

As the consequence, reclamation of the owning vnode could go in
parallel, in particular, the call to vnode_destroy_vobject(), which
deallocates the vm object and zeroes the v_bufobj->bo_object. Note
that the pages wired by the buffer are left wired and can be safely
freed by the vfs_vmio_release() without the need for the vm object
lock. Also, seeing stale pointer to the v_object is safe due to vm
object type stability.

Check for bo_bufobj != NULL and cache the value in local variable to
avoid trying to lock NULL vm object.

Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

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Merge from head@274682

Revert somewhat hackish geom_disk optimization, committed as part of r256880,
and the following r273143 commit, supposed to workaround introduced issue by
quite innocent-looking change.

While there

Revert somewhat hackish geom_disk optimization, committed as part of r256880,
and the following r273143 commit, supposed to workaround introduced issue by
quite innocent-looking change.

While there is no clear understanding why, but r273143 is accused in data
corruption in some environments with high I/O load. I personally don't see
any problem in that commit, and possibly it is just a trigger to some other
bug somewhere, but better safe then sorry for now.

Requested by: scottl@
MFC after: 3 days

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IFC @r273206