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23 October 2021, 00:29:24 UTC
Revision 9b57988db9b2c81794546cb792133f0cfd064ea8 authored by Eric Sandeen on 28 October 2006, 17:38:28 UTC, committed by Linus Torvalds on 28 October 2006, 18:30:51 UTC 
[PATCH] jbd2: journal_dirty_data re-check for unmapped buffers
 
When running several fsx's and other filesystem stress tests, we found
cases where an unmapped buffer was still being sent to submit_bh by the
ext3 dirty data journaling code.

I saw this happen in two ways, both related to another thread doing a
truncate which would unmap the buffer in question.

Either we would get into journal_dirty_data with a bh which was already
unmapped (although journal_dirty_data_fn had checked for this earlier, the
state was not locked at that point), or it would get unmapped in the middle
of journal_dirty_data when we dropped locks to call sync_dirty_buffer.

By re-checking for mapped state after we've acquired the bh state lock, we
should avoid these races.  If we find a buffer which is no longer mapped,
we essentially ignore it, because journal_unmap_buffer has already decided
that this buffer can go away.

I've also added tracepoints in these two cases, and made a couple other
tracepoint changes that I found useful in debugging this.

Signed-off-by: Eric Sandeen <esandeen@redhat.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent f58a74d
Raw File
Tip revision: 9b57988db9b2c81794546cb792133f0cfd064ea8 authored by Eric Sandeen on 28 October 2006, 17:38:28 UTC
[PATCH] jbd2: journal_dirty_data re-check for unmapped buffers
Tip revision: 9b57988
Kbuild 
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
# 1) Generate asm-offsets.h

#####
# 1) Generate asm-offsets.h
#

offsets-file := include/asm-$(ARCH)/asm-offsets.h

always  := $(offsets-file)
targets := $(offsets-file)
targets += arch/$(ARCH)/kernel/asm-offsets.s

# Default sed regexp - multiline due to syntax constraints
define sed-y
	"/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"
endef
# Override default regexp for specific architectures
sed-$(CONFIG_MIPS) := "/^@@@/{s/^@@@//; s/ \#.*\$$//; p;}"

quiet_cmd_offsets = GEN     $@
define cmd_offsets
	(set -e; \
	 echo "#ifndef __ASM_OFFSETS_H__"; \
	 echo "#define __ASM_OFFSETS_H__"; \
	 echo "/*"; \
	 echo " * DO NOT MODIFY."; \
	 echo " *"; \
	 echo " * This file was generated by Kbuild"; \
	 echo " *"; \
	 echo " */"; \
	 echo ""; \
	 sed -ne $(sed-y) $<; \
	 echo ""; \
	 echo "#endif" ) > $@
endef

# We use internal kbuild rules to avoid the "is up to date" message from make
arch/$(ARCH)/kernel/asm-offsets.s: arch/$(ARCH)/kernel/asm-offsets.c FORCE
	$(Q)mkdir -p $(dir $@)
	$(call if_changed_dep,cc_s_c)

$(obj)/$(offsets-file): arch/$(ARCH)/kernel/asm-offsets.s Kbuild
	$(Q)mkdir -p $(dir $@)
	$(call cmd,offsets)
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