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authorChris Mason <clm@fb.com>2016-05-16 09:21:01 -0700
committerChris Mason <clm@fb.com>2016-05-26 13:23:59 -0700
commit56244ef151c3cd11f505020ab0b3f45454363bcc (patch)
tree4ee1dea828e6be4e0dd746dfe19d40a0790e303d
parent9257b4ca9dff074918164e4fa10e9001c62bc27a (diff)
Btrfs: fix handling of faults from btrfs_copy_from_user
When btrfs_copy_from_user isn't able to copy all of the pages, we need to adjust our accounting to reflect the work that was actually done. Commit 2e78c927d79 changed around the decisions a little and we ended up skipping the accounting adjustments some of the time. This commit makes sure that when we don't copy anything at all, we still hop into the adjustments, and switches to release_bytes instead of write_bytes, since write_bytes isn't aligned. The accounting errors led to warnings during btrfs_destroy_inode: [ 70.847532] WARNING: CPU: 10 PID: 514 at fs/btrfs/inode.c:9350 btrfs_destroy_inode+0x2b3/0x2c0 [ 70.847536] Modules linked in: i2c_piix4 virtio_net i2c_core input_leds button led_class serio_raw acpi_cpufreq sch_fq_codel autofs4 virtio_blk [ 70.847538] CPU: 10 PID: 514 Comm: umount Tainted: G W 4.6.0-rc6_00062_g2997da1-dirty #23 [ 70.847539] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.0-1.fc24 04/01/2014 [ 70.847542] 0000000000000000 ffff880ff5cafab8 ffffffff8149d5e9 0000000000000202 [ 70.847543] 0000000000000000 0000000000000000 0000000000000000 ffff880ff5cafb08 [ 70.847547] ffffffff8107bdfd ffff880ff5cafaf8 000024868120013d ffff880ff5cafb28 [ 70.847547] Call Trace: [ 70.847550] [<ffffffff8149d5e9>] dump_stack+0x51/0x78 [ 70.847551] [<ffffffff8107bdfd>] __warn+0xfd/0x120 [ 70.847553] [<ffffffff8107be3d>] warn_slowpath_null+0x1d/0x20 [ 70.847555] [<ffffffff8139c9e3>] btrfs_destroy_inode+0x2b3/0x2c0 [ 70.847556] [<ffffffff812003a1>] ? __destroy_inode+0x71/0x140 [ 70.847558] [<ffffffff812004b3>] destroy_inode+0x43/0x70 [ 70.847559] [<ffffffff810b7b5f>] ? wake_up_bit+0x2f/0x40 [ 70.847560] [<ffffffff81200c68>] evict+0x148/0x1d0 [ 70.847562] [<ffffffff81398ade>] ? start_transaction+0x3de/0x460 [ 70.847564] [<ffffffff81200d49>] dispose_list+0x59/0x80 [ 70.847565] [<ffffffff81201ba0>] evict_inodes+0x180/0x190 [ 70.847566] [<ffffffff812191ff>] ? __sync_filesystem+0x3f/0x50 [ 70.847568] [<ffffffff811e95f8>] generic_shutdown_super+0x48/0x100 [ 70.847569] [<ffffffff810b75c0>] ? woken_wake_function+0x20/0x20 [ 70.847571] [<ffffffff811e9796>] kill_anon_super+0x16/0x30 [ 70.847573] [<ffffffff81365cde>] btrfs_kill_super+0x1e/0x130 [ 70.847574] [<ffffffff811e99be>] deactivate_locked_super+0x4e/0x90 [ 70.847576] [<ffffffff811e9e61>] deactivate_super+0x51/0x70 [ 70.847577] [<ffffffff8120536f>] cleanup_mnt+0x3f/0x80 [ 70.847579] [<ffffffff81205402>] __cleanup_mnt+0x12/0x20 [ 70.847581] [<ffffffff81098358>] task_work_run+0x68/0xa0 [ 70.847582] [<ffffffff810022b6>] exit_to_usermode_loop+0xd6/0xe0 [ 70.847583] [<ffffffff81002e1d>] do_syscall_64+0xbd/0x170 [ 70.847586] [<ffffffff817d4dbc>] entry_SYSCALL64_slow_path+0x25/0x25 This is the test program I used to force short returns from btrfs_copy_from_user void *dontneed(void *arg) { char *p = arg; int ret; while(1) { ret = madvise(p, BUFSIZE/4, MADV_DONTNEED); if (ret) { perror("madvise"); exit(1); } } } int main(int ac, char **av) { int ret; int fd; char *filename; unsigned long offset; char *buf; int i; pthread_t tid; if (ac != 2) { fprintf(stderr, "usage: dammitdave filename\n"); exit(1); } buf = mmap(NULL, BUFSIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); if (buf == MAP_FAILED) { perror("mmap"); exit(1); } memset(buf, 'a', BUFSIZE); filename = av[1]; ret = pthread_create(&tid, NULL, dontneed, buf); if (ret) { fprintf(stderr, "error %d from pthread_create\n", ret); exit(1); } ret = pthread_detach(tid); if (ret) { fprintf(stderr, "pthread detach failed %d\n", ret); exit(1); } while (1) { fd = open(filename, O_RDWR | O_CREAT, 0600); if (fd < 0) { perror("open"); exit(1); } for (i = 0; i < ROUNDS; i++) { int this_write = BUFSIZE; offset = rand() % MAXSIZE; ret = pwrite(fd, buf, this_write, offset); if (ret < 0) { perror("pwrite"); exit(1); } else if (ret != this_write) { fprintf(stderr, "short write to %s offset %lu ret %d\n", filename, offset, ret); exit(1); } if (i == ROUNDS - 1) { ret = sync_file_range(fd, offset, 4096, SYNC_FILE_RANGE_WRITE); if (ret < 0) { perror("sync_file_range"); exit(1); } } } ret = ftruncate(fd, 0); if (ret < 0) { perror("ftruncate"); exit(1); } ret = close(fd); if (ret) { perror("close"); exit(1); } ret = unlink(filename); if (ret) { perror("unlink"); exit(1); } } return 0; } Signed-off-by: Chris Mason <clm@fb.com> Reported-by: Dave Jones <dsj@fb.com> Fixes: 2e78c927d79333f299a8ac81c2fd2952caeef335 cc: stable@vger.kernel.org # v4.6 Signed-off-by: Chris Mason <clm@fb.com>
-rw-r--r--fs/btrfs/file.c27
1 files changed, 17 insertions, 10 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 1933e8b07ed7..159a93450e26 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1596,6 +1596,13 @@ again:
copied = btrfs_copy_from_user(pos, write_bytes, pages, i);
+ num_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
+ reserve_bytes);
+ dirty_sectors = round_up(copied + sector_offset,
+ root->sectorsize);
+ dirty_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
+ dirty_sectors);
+
/*
* if we have trouble faulting in the pages, fall
* back to one page at a time
@@ -1605,6 +1612,7 @@ again:
if (copied == 0) {
force_page_uptodate = true;
+ dirty_sectors = 0;
dirty_pages = 0;
} else {
force_page_uptodate = false;
@@ -1615,20 +1623,19 @@ again:
/*
* If we had a short copy we need to release the excess delaloc
* bytes we reserved. We need to increment outstanding_extents
- * because btrfs_delalloc_release_space will decrement it, but
+ * because btrfs_delalloc_release_space and
+ * btrfs_delalloc_release_metadata will decrement it, but
* we still have an outstanding extent for the chunk we actually
* managed to copy.
*/
- num_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
- reserve_bytes);
- dirty_sectors = round_up(copied + sector_offset,
- root->sectorsize);
- dirty_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
- dirty_sectors);
-
if (num_sectors > dirty_sectors) {
- release_bytes = (write_bytes - copied)
- & ~((u64)root->sectorsize - 1);
+ /*
+ * we round down because we don't want to count
+ * any partial blocks actually sent through the
+ * IO machines
+ */
+ release_bytes = round_down(release_bytes - copied,
+ root->sectorsize);
if (copied > 0) {
spin_lock(&BTRFS_I(inode)->lock);
BTRFS_I(inode)->outstanding_extents++;