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fusefs: fix a page fault with writeback cacheing

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When truncating a file downward through a dirty buffer, it's neccessary to
update the buffer's b->dirtyend.

Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Alan Somers 2019-06-11 23:46:31 +00:00
parent a87e0831ab
commit 93c0c1d4ce
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/projects/fuse2/; revision=348978
2 changed files with 40 additions and 5 deletions
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1
sys/fs/fuse/fuse_node.c
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@ -415,6 +415,7 @@ fuse_vnode_setsize(struct vnode *vp, off_t newsize)
goto out; /* Nothing to do */
MPASS(bp->b_flags & B_VMIO);
vfs_bio_clrbuf(bp);
bp->b_dirtyend = MIN(bp->b_dirtyend, newsize - lbn * iosize);
}
out:
if (bp)

44
tests/sys/fs/fusefs/io.cc
View File

@ -59,10 +59,10 @@ Io(): m_backing_fd(-1), m_control_fd(-1) {};
void SetUp()
{
m_backing_fd = open("backing_file", O_RDWR | O_CREAT | O_TRUNC);
m_backing_fd = open("backing_file", O_RDWR | O_CREAT | O_TRUNC, 0644);
if (m_backing_fd < 0)
FAIL() << strerror(errno);
m_control_fd = open("control", O_RDWR | O_CREAT | O_TRUNC);
m_control_fd = open("control", O_RDWR | O_CREAT | O_TRUNC, 0644);
if (m_control_fd < 0)
FAIL() << strerror(errno);
srandom(22'9'1982); // Seed with my birthday
@ -251,12 +251,12 @@ TEST_F(Io, read_hole_from_cached_block)
}
/*
* Reliable panic; I don't yet know why.
* Disabled because it panics.
* Truncating a file into a dirty buffer should not causing anything untoward
* to happen when that buffer is eventually flushed.
*
* fsx -WR -P /tmp -S839 -d -N6 fsx.bin
*/
TEST_F(Io, DISABLED_fault_on_nofault_entry)
TEST_F(Io, truncate_into_dirty_buffer)
{
off_t wofs0 = 0x3bad7;
ssize_t wsize0 = 0x4529;
@ -274,3 +274,37 @@ TEST_F(Io, DISABLED_fault_on_nofault_entry)
do_ftruncate(truncsize1);
close(m_test_fd);
}
/*
* Truncating a file into a dirty buffer should not causing anything untoward
* to happen when that buffer is eventually flushed, even when the buffer's
* dirty_off is > 0.
*
* Based on this command with a few steps removed:
* fsx -WR -P /tmp -S677 -d -N8 fsx.bin
*/
TEST_F(Io, truncate_into_dirty_buffer2)
{
off_t truncsize0 = 0x344f3;
off_t wofs = 0x2790c;
ssize_t wsize = 0xd86a;
off_t truncsize1 = 0x2de38;
off_t rofs2 = 0x1fd7a;
ssize_t rsize2 = 0xc594;
off_t truncsize2 = 0x31e71;
/* Sets the file size to something larger than the next write */
do_ftruncate(truncsize0);
/*
* Creates a dirty buffer. The part in lbn 2 doesn't flush
* synchronously.
*/
do_write(wsize, wofs);
/* Truncates part of the dirty buffer created in step 2 */
do_ftruncate(truncsize1);
/* XXX ?I don't know why this is necessary? */
do_read(rsize2, rofs2);
/* Truncates the dirty buffer */
do_ftruncate(truncsize2);
close(m_test_fd);
}