| Message ID | 1448589441-19321-1-git-send-email-junxiao.bi@oracle.com |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Fri 27-11-15 09:57:21, Junxiao Bi wrote: > commit de92c8c ("jbd2: speedup jbd2_journal_get_[write|undo]_access()") > introduced jbd2_write_access_granted() to improve write|undo_access > speed, but missed to check the status of b_committed_data which caused > a kernel panic on ocfs2. Thanks for debugging this! Just a few minor nits: 1) Please use at least 12 characters of the commit hash - i.e. de92c8caf16c - that is pretty much guaranteed to stay unique for the lifetime of Linux. Using just 7 characters will become non-unique with high probability rather soon. 2) Send this patch to Ted Tso as well as he is the one merging jbd2 patches. 3) The fact that OCFS2 hit this problem means that it is mixing jbd2_journal_get_write_access() and jbd2_journal_get_undo_access() for the same buffer. That is slightly suspicious to me. Not that it would be outright bug but you have to account for the fact that someone can be modifying the buffer data while you are getting undo access... 4) Some other comments below in the code. > diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c > index 6b8338e..4750bda 100644 > --- a/fs/jbd2/transaction.c > +++ b/fs/jbd2/transaction.c > @@ -1009,7 +1009,8 @@ out: > } > > /* Fast check whether buffer is already attached to the required transaction */ > -static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh) > +static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh, > + int undo) ^^^ Use 'bool' please. The function is already using bools so it is good for consistency. > { > struct journal_head *jh; > bool ret = false; > @@ -1036,6 +1037,8 @@ static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh) > jh = READ_ONCE(bh->b_private); > if (!jh) > goto out; Short comment here please. Like: /* For undo access buffer must have data copied */ > + if (undo && !jh->b_committed_data) > + goto out; > if (jh->b_transaction != handle->h_transaction && > jh->b_next_transaction != handle->h_transaction) > goto out; > @@ -1073,7 +1076,7 @@ int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh) > struct journal_head *jh; > int rc; > > - if (jbd2_write_access_granted(handle, bh)) > + if (jbd2_write_access_granted(handle, bh, 0)) Here 'false' instead of 0. > JBUFFER_TRACE(jh, "entry"); > - if (jbd2_write_access_granted(handle, bh)) > + if (jbd2_write_access_granted(handle, bh, 1)) Here 'true' instead of 1. Thanks. Honza
On 11/27/2015 04:45 PM, Jan Kara wrote: > On Fri 27-11-15 09:57:21, Junxiao Bi wrote: >> commit de92c8c ("jbd2: speedup jbd2_journal_get_[write|undo]_access()") >> introduced jbd2_write_access_granted() to improve write|undo_access >> speed, but missed to check the status of b_committed_data which caused >> a kernel panic on ocfs2. > > Thanks for debugging this! Just a few minor nits: > > 1) Please use at least 12 characters of the commit hash - i.e. de92c8caf16c > - that is pretty much guaranteed to stay unique for the lifetime of Linux. > Using just 7 characters will become non-unique with high probability rather > soon. I saw this report from checkpatch.pl. Since there have "patch subject", so i didn't modify it. I will update it in v2 patch. > > 2) Send this patch to Ted Tso as well as he is the one merging jbd2 > patches. OK. > > 3) The fact that OCFS2 hit this problem means that it is mixing > jbd2_journal_get_write_access() and jbd2_journal_get_undo_access() for the > same buffer. That is slightly suspicious to me. Not that it would be > outright bug but you have to account for the fact that someone can be > modifying the buffer data while you are getting undo access... I am not sure about this. Mark involved this in commit b4414eea0e ("ocfs2: Clear undo bits when local alloc is freed"). Mark, is mixing using undo/write access a bug? > > 4) Some other comments below in the code. > >> diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c >> index 6b8338e..4750bda 100644 >> --- a/fs/jbd2/transaction.c >> +++ b/fs/jbd2/transaction.c >> @@ -1009,7 +1009,8 @@ out: >> } >> >> /* Fast check whether buffer is already attached to the required transaction */ >> -static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh) >> +static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh, >> + int undo) > ^^^ > Use 'bool' please. The function is already using bools so it is good for > consistency. Will fix this in v2. Thanks, Junxiao. > >> { >> struct journal_head *jh; >> bool ret = false; >> @@ -1036,6 +1037,8 @@ static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh) >> jh = READ_ONCE(bh->b_private); >> if (!jh) >> goto out; > > Short comment here please. Like: > > /* For undo access buffer must have data copied */ > >> + if (undo && !jh->b_committed_data) >> + goto out; >> if (jh->b_transaction != handle->h_transaction && >> jh->b_next_transaction != handle->h_transaction) >> goto out; >> @@ -1073,7 +1076,7 @@ int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh) >> struct journal_head *jh; >> int rc; >> >> - if (jbd2_write_access_granted(handle, bh)) >> + if (jbd2_write_access_granted(handle, bh, 0)) > > Here 'false' instead of 0. > >> JBUFFER_TRACE(jh, "entry"); >> - if (jbd2_write_access_granted(handle, bh)) >> + if (jbd2_write_access_granted(handle, bh, 1)) > > Here 'true' instead of 1. > > Thanks. > > Honza > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index 6b8338e..4750bda 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -1009,7 +1009,8 @@ out: } /* Fast check whether buffer is already attached to the required transaction */ -static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh) +static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh, + int undo) { struct journal_head *jh; bool ret = false; @@ -1036,6 +1037,8 @@ static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh) jh = READ_ONCE(bh->b_private); if (!jh) goto out; + if (undo && !jh->b_committed_data) + goto out; if (jh->b_transaction != handle->h_transaction && jh->b_next_transaction != handle->h_transaction) goto out; @@ -1073,7 +1076,7 @@ int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh) struct journal_head *jh; int rc; - if (jbd2_write_access_granted(handle, bh)) + if (jbd2_write_access_granted(handle, bh, 0)) return 0; jh = jbd2_journal_add_journal_head(bh); @@ -1210,7 +1213,7 @@ int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh) char *committed_data = NULL; JBUFFER_TRACE(jh, "entry"); - if (jbd2_write_access_granted(handle, bh)) + if (jbd2_write_access_granted(handle, bh, 1)) return 0; jh = jbd2_journal_add_journal_head(bh);
commit de92c8c ("jbd2: speedup jbd2_journal_get_[write|undo]_access()") introduced jbd2_write_access_granted() to improve write|undo_access speed, but missed to check the status of b_committed_data which caused a kernel panic on ocfs2. [ 6538.405938] ------------[ cut here ]------------ [ 6538.406686] kernel BUG at fs/ocfs2/suballoc.c:2400! [ 6538.406686] invalid opcode: 0000 [#1] SMP [ 6538.406686] Modules linked in: ocfs2 nfsd lockd grace nfs_acl auth_rpcgss sunrpc autofs4 ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm ocfs2_nodemanager ocfs2_stackglue configfs sd_mod sg ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables be2iscsi iscsi_boot_sysfs bnx2i cnic uio cxgb4i cxgb4 cxgb3i libcxgbi cxgb3 mdio ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad ib_core ib_addr ipv6 iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi ppdev xen_kbdfront xen_netfront xen_fbfront parport_pc parport pcspkr i2c_piix4 acpi_cpufreq ext4 jbd2 mbcache xen_blkfront floppy pata_acpi ata_generic ata_piix cirrus ttm drm_kms_helper drm fb_sys_fops sysimgblt sysfillrect i2c_core syscopyarea dm_mirror dm_region_hash dm_log dm_mod [ 6538.406686] CPU: 1 PID: 16265 Comm: mmap_truncate Not tainted 4.3.0 #1 [ 6538.406686] Hardware name: Xen HVM domU, BIOS 4.3.1OVM 05/14/2014 [ 6538.406686] task: ffff88007c2bab00 ti: ffff880075b78000 task.ti: ffff880075b78000 [ 6538.406686] RIP: 0010:[<ffffffffa06a286b>] [<ffffffffa06a286b>] ocfs2_block_group_clear_bits+0x23b/0x250 [ocfs2] [ 6538.406686] RSP: 0018:ffff880075b7b7f8 EFLAGS: 00010246 [ 6538.406686] RAX: ffff8800760c5b40 RBX: ffff88006c06a000 RCX: ffffffffa06e6df0 [ 6538.406686] RDX: 0000000000000000 RSI: ffff88007a6f6ea0 RDI: ffff88007a760430 [ 6538.406686] RBP: ffff880075b7b878 R08: 0000000000000002 R09: 0000000000000001 [ 6538.406686] R10: ffffffffa06769be R11: 0000000000000000 R12: 0000000000000001 [ 6538.406686] R13: ffffffffa06a1750 R14: 0000000000000001 R15: ffff88007a6f6ea0 [ 6538.406686] FS: 00007f17fde30720(0000) GS:ffff88007f040000(0000) knlGS:0000000000000000 [ 6538.406686] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 6538.406686] CR2: 0000000000601730 CR3: 000000007aea0000 CR4: 00000000000406e0 [ 6538.406686] Stack: [ 6538.406686] ffff88007c2bb5b0 ffff880075b7b8e0 ffff88007a7604b0 ffff88006c640800 [ 6538.406686] ffff88007a7604b0 ffff880075d77390 0000000075b7b878 ffffffffa06a309d [ 6538.406686] ffff880075d752d8 ffff880075b7b990 ffff880075b7b898 0000000000000000 [ 6538.406686] Call Trace: [ 6538.406686] [<ffffffffa06a309d>] ? ocfs2_read_group_descriptor+0x6d/0xa0 [ocfs2] [ 6538.406686] [<ffffffffa06a3654>] _ocfs2_free_suballoc_bits+0xe4/0x320 [ocfs2] [ 6538.406686] [<ffffffffa06a1750>] ? ocfs2_put_slot+0xf0/0xf0 [ocfs2] [ 6538.406686] [<ffffffffa06a397e>] _ocfs2_free_clusters+0xee/0x210 [ocfs2] [ 6538.406686] [<ffffffffa06a1750>] ? ocfs2_put_slot+0xf0/0xf0 [ocfs2] [ 6538.406686] [<ffffffffa06a1750>] ? ocfs2_put_slot+0xf0/0xf0 [ocfs2] [ 6538.406686] [<ffffffffa0682d50>] ? ocfs2_extend_trans+0x50/0x1a0 [ocfs2] [ 6538.406686] [<ffffffffa06a3ad5>] ocfs2_free_clusters+0x15/0x20 [ocfs2] [ 6538.406686] [<ffffffffa065072c>] ocfs2_replay_truncate_records+0xfc/0x290 [ocfs2] [ 6538.406686] [<ffffffffa06843ac>] ? ocfs2_start_trans+0xec/0x1d0 [ocfs2] [ 6538.406686] [<ffffffffa0654600>] __ocfs2_flush_truncate_log+0x140/0x2d0 [ocfs2] [ 6538.406686] [<ffffffffa0654394>] ? ocfs2_reserve_blocks_for_rec_trunc.clone.0+0x44/0x170 [ocfs2] [ 6538.406686] [<ffffffffa065acd4>] ocfs2_remove_btree_range+0x374/0x630 [ocfs2] [ 6538.406686] [<ffffffffa017486b>] ? jbd2_journal_stop+0x25b/0x470 [jbd2] [ 6538.406686] [<ffffffffa065d5b5>] ocfs2_commit_truncate+0x305/0x670 [ocfs2] [ 6538.406686] [<ffffffffa0683430>] ? ocfs2_journal_access_eb+0x20/0x20 [ocfs2] [ 6538.406686] [<ffffffffa067adb7>] ocfs2_truncate_file+0x297/0x380 [ocfs2] [ 6538.406686] [<ffffffffa01759e4>] ? jbd2_journal_begin_ordered_truncate+0x64/0xc0 [jbd2] [ 6538.406686] [<ffffffffa067c7a2>] ocfs2_setattr+0x572/0x860 [ocfs2] [ 6538.406686] [<ffffffff810e4a3f>] ? current_fs_time+0x3f/0x50 [ 6538.406686] [<ffffffff812124b7>] notify_change+0x1d7/0x340 [ 6538.406686] [<ffffffff8121abf9>] ? generic_getxattr+0x79/0x80 [ 6538.406686] [<ffffffff811f5876>] do_truncate+0x66/0x90 [ 6538.406686] [<ffffffff81120e30>] ? __audit_syscall_entry+0xb0/0x110 [ 6538.406686] [<ffffffff811f5bb3>] do_sys_ftruncate.clone.0+0xf3/0x120 [ 6538.406686] [<ffffffff811f5bee>] SyS_ftruncate+0xe/0x10 [ 6538.406686] [<ffffffff816aa2ae>] entry_SYSCALL_64_fastpath+0x12/0x71 [ 6538.406686] Code: 28 48 81 ee b0 04 00 00 48 8b 92 50 fb ff ff 48 8b 80 b0 03 00 00 48 39 90 88 00 00 00 0f 84 30 fe ff ff 0f 0b eb fe 0f 0b eb fe <0f> 0b 0f 1f 00 eb fb 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 [ 6538.406686] RIP [<ffffffffa06a286b>] ocfs2_block_group_clear_bits+0x23b/0x250 [ocfs2] [ 6538.406686] RSP <ffff880075b7b7f8> [ 6538.691128] ---[ end trace 31cd7011d6770d7e ]--- [ 6538.694492] Kernel panic - not syncing: Fatal exception [ 6538.695484] Kernel Offset: disabled Fixes: de92c8c("jbd2: speedup jbd2_journal_get_[write|undo]_access()") Cc: <stable@vger.kernel.org> Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com> --- fs/jbd2/transaction.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)