66 lines
1.9 KiB
Diff
66 lines
1.9 KiB
Diff
From 4c4679fc02744ec3955e88faf5e8b6844fa8cbd3 Mon Sep 17 00:00:00 2001
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From: Dmitry Monakhov <dmonakhov@openvz.org>
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Date: Sat, 29 Sep 2012 00:55:23 -0400
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Subject: [PATCH 06/13] ext4: serialize unlocked dio reads with truncate
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Current serialization will works only for DIO which holds
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i_mutex, but nonlocked DIO following race is possible:
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dio_nolock_read_task truncate_task
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->ext4_setattr()
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->inode_dio_wait()
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->ext4_ext_direct_IO
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->ext4_ind_direct_IO
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->__blockdev_direct_IO
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->ext4_get_block
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->truncate_setsize()
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->ext4_truncate()
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#alloc truncated blocks
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#to other inode
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->submit_io()
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#INFORMATION LEAK
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In order to serialize with unlocked DIO reads we have to
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rearrange wait sequence
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1) update i_size first
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2) if i_size about to be reduced wait for outstanding DIO requests
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3) and only after that truncate inode blocks
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Reviewed-by: Jan Kara <jack@suse.cz>
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Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
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Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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(cherry picked from commit 1c9114f9c0f10f58dd7e568a7152025af47b27e5)
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---
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fs/ext4/inode.c | 7 +++++--
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1 file changed, 5 insertions(+), 2 deletions(-)
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diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
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index 2bd7526..b84322d 100644
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--- a/fs/ext4/inode.c
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+++ b/fs/ext4/inode.c
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@@ -4277,7 +4277,6 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
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}
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if (attr->ia_valid & ATTR_SIZE) {
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- inode_dio_wait(inode);
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if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
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struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
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@@ -4326,8 +4325,12 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
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}
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if (attr->ia_valid & ATTR_SIZE) {
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- if (attr->ia_size != i_size_read(inode))
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+ if (attr->ia_size != i_size_read(inode)) {
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truncate_setsize(inode, attr->ia_size);
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+ /* Inode size will be reduced, wait for dio in flight */
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+ if (orphan)
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+ inode_dio_wait(inode);
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+ }
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ext4_truncate(inode);
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}
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--
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1.7.12.rc0.22.gcdd159b
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