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fix various issues mounting btrfs devices with subvolumes (#656465)

This commit is contained in:
Kyle McMartin 2010-12-10 10:22:27 -05:00
parent 49bf2616cc
commit 7ad304ff1f
4 changed files with 232 additions and 0 deletions
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65
btrfs-fix-error-handling-in-btrfs_get_sb.patch Normal file
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@ -0,0 +1,65 @@
From 1299757412533c8e2ea1d00a1e77944bc87ff39d Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@redhat.com>
Date: Fri, 22 Oct 2010 15:26:53 -0400
Subject: [PATCH 1/3] Btrfs: fix error handling in btrfs_get_sb
If we failed to find the root subvol id, or the subvol=<name>, we would
deactivate the locked super and close the devices. The problem is at this point
we have gotten the SB all setup, which includes setting super_operations, so
when we'd deactiveate the super, we'd do a close_ctree() which closes the
devices, so we'd end up closing the devices twice. So if you do something like
this
mount /dev/sda1 /mnt/test1
mount /dev/sda1 /mnt/test2 -o subvol=xxx
umount /mnt/test1
it would blow up (if subvol xxx doesn't exist). This patch fixes that problem.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
---
fs/btrfs/super.c | 7 +++----
1 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 1776dbd..185702f 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -629,7 +629,7 @@ static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
if (IS_ERR(root)) {
error = PTR_ERR(root);
deactivate_locked_super(s);
- goto error;
+ goto error_free_subvol_name;
}
/* if they gave us a subvolume name bind mount into that */
if (strcmp(subvol_name, ".")) {
@@ -643,14 +643,14 @@ static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
deactivate_locked_super(s);
error = PTR_ERR(new_root);
dput(root);
- goto error_close_devices;
+ goto error_free_subvol_name;
}
if (!new_root->d_inode) {
dput(root);
dput(new_root);
deactivate_locked_super(s);
error = -ENXIO;
- goto error_close_devices;
+ goto error_free_subvol_name;
}
dput(root);
root = new_root;
@@ -668,7 +668,6 @@ error_close_devices:
btrfs_close_devices(fs_devices);
error_free_subvol_name:
kfree(subvol_name);
-error:
return error;
}
--
1.7.3.3

37
btrfs-fix-race-between-btrfs_get_sb-and-umount.patch Normal file
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@ -0,0 +1,37 @@
From 34825fb2c891ee56fdde84000f0b1bc83a12f42f Mon Sep 17 00:00:00 2001
From: Ian Kent <raven@themaw.net>
Date: Mon, 22 Nov 2010 02:21:38 +0000
Subject: [PATCH 2/3] Btrfs - fix race between btrfs_get_sb() and umount
When mounting a btrfs file system btrfs_test_super() may attempt to
use sb->s_fs_info, the btrfs root, of a super block that is going away
and that has had the btrfs root set to NULL in its ->put_super(). But
if the super block is going away it cannot be an existing super block
so we can return false in this case.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---
fs/btrfs/super.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 185702f..b169698 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -551,6 +551,12 @@ static int btrfs_test_super(struct super_block *s, void *data)
struct btrfs_fs_devices *test_fs_devices = data;
struct btrfs_root *root = btrfs_sb(s);
+ /*
+ * If this super block is going away, return false as it
+ * can't match as an existing super block.
+ */
+ if (!atomic_read(&s->s_active))
+ return 0;
return root->fs_info->fs_devices == test_fs_devices;
}
--
1.7.3.3

118
btrfs-setup-blank-root-and-fs_info-for-mount-time.patch Normal file
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@ -0,0 +1,118 @@
From 7f9f05e1f4cd9a625bc35b117a239d9b0cbe4a03 Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@redhat.com>
Date: Fri, 19 Nov 2010 14:59:15 -0500
Subject: [PATCH 3/3] Btrfs: setup blank root and fs_info for mount time
There is a problem with how we use sget, it searches through the list of supers
attached to the fs_type looking for a super with the same fs_devices as what
we're trying to mount. This depends on sb->s_fs_info being filled, but we don't
fill that in until we get to btrfs_fill_super, so we could hit supers on the
fs_type super list that have a null s_fs_info. In order to fix that we need to
go ahead and setup a blank root with a blank fs_info to hold fs_devices, that
way our test will work out right and then we can set s_fs_info in
btrfs_set_super, and then open_ctree will simply use our pre-allocated root and
fs_info when setting everything up. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---
fs/btrfs/disk-io.c | 6 ++----
fs/btrfs/super.c | 34 +++++++++++++++++++++++++++++++---
2 files changed, 33 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 64f1008..65efa04 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1539,10 +1539,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
GFP_NOFS);
struct btrfs_root *csum_root = kzalloc(sizeof(struct btrfs_root),
GFP_NOFS);
- struct btrfs_root *tree_root = kzalloc(sizeof(struct btrfs_root),
- GFP_NOFS);
- struct btrfs_fs_info *fs_info = kzalloc(sizeof(*fs_info),
- GFP_NOFS);
+ struct btrfs_root *tree_root = btrfs_sb(sb);
+ struct btrfs_fs_info *fs_info = tree_root->fs_info;
struct btrfs_root *chunk_root = kzalloc(sizeof(struct btrfs_root),
GFP_NOFS);
struct btrfs_root *dev_root = kzalloc(sizeof(struct btrfs_root),
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index b169698..6479db9 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -548,7 +548,7 @@ static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
static int btrfs_test_super(struct super_block *s, void *data)
{
- struct btrfs_fs_devices *test_fs_devices = data;
+ struct btrfs_root *test_root = data;
struct btrfs_root *root = btrfs_sb(s);
/*
@@ -557,9 +557,17 @@ static int btrfs_test_super(struct super_block *s, void *data)
*/
if (!atomic_read(&s->s_active))
return 0;
- return root->fs_info->fs_devices == test_fs_devices;
+ return root->fs_info->fs_devices == test_root->fs_info->fs_devices;
}
+static int btrfs_set_super(struct super_block *s, void *data)
+{
+ s->s_fs_info = data;
+
+ return set_anon_super(s, data);
+}
+
+
/*
* Find a superblock for the given device / mount point.
*
@@ -573,6 +581,8 @@ static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
struct super_block *s;
struct dentry *root;
struct btrfs_fs_devices *fs_devices = NULL;
+ struct btrfs_root *tree_root = NULL;
+ struct btrfs_fs_info *fs_info = NULL;
fmode_t mode = FMODE_READ;
char *subvol_name = NULL;
u64 subvol_objectid = 0;
@@ -601,8 +611,24 @@ static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
goto error_close_devices;
}
+ /*
+ * Setup a dummy root and fs_info for test/set super. This is because
+ * we don't actually fill this stuff out until open_ctree, but we need
+ * it for searching for existing supers, so this lets us do that and
+ * then open_ctree will properly initialize everything later.
+ */
+ fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
+ tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
+ if (!fs_info || !tree_root) {
+ error = -ENOMEM;
+ goto error_close_devices;
+ }
+ fs_info->tree_root = tree_root;
+ fs_info->fs_devices = fs_devices;
+ tree_root->fs_info = fs_info;
+
bdev = fs_devices->latest_bdev;
- s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
+ s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
if (IS_ERR(s))
goto error_s;
@@ -672,6 +698,8 @@ error_s:
error = PTR_ERR(s);
error_close_devices:
btrfs_close_devices(fs_devices);
+ kfree(fs_info);
+ kfree(tree_root);
error_free_subvol_name:
kfree(subvol_name);
return error;
--
1.7.3.3

12
kernel.spec
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@ -743,6 +743,10 @@ Patch12430: sched-cure-more-NO_HZ-load-average-woes.patch
Patch12431: orinoco-initialise-priv_hw-before-assigning-the-interrupt.patch
Patch12435: btrfs-fix-error-handling-in-btrfs_get_sb.patch
Patch12436: btrfs-fix-race-between-btrfs_get_sb-and-umount.patch
Patch12437: btrfs-setup-blank-root-and-fs_info-for-mount-time.patch
%endif
BuildRoot: %{_tmppath}/kernel-%{KVERREL}-root
@ -1195,6 +1199,11 @@ ApplyPatch linux-2.6-32bit-mmap-exec-randomization.patch
# btrfs
# rhbz#656465
ApplyPatch btrfs-fix-error-handling-in-btrfs_get_sb.patch
ApplyPatch btrfs-fix-race-between-btrfs_get_sb-and-umount.patch
ApplyPatch btrfs-setup-blank-root-and-fs_info-for-mount-time.patch
# eCryptfs
@ -1999,6 +2008,9 @@ fi
# || ||
%changelog
* Fri Dec 10 2010 Kyle McMartin <kyle@redhat.com>
- Fix various issues mounting btrfs devices with subvolumes (#656465)
* Thu Dec 09 2010 Kyle McMartin <kyle@redhat.com> 2.6.36.2-13
- Linux stable 2.6.36.2
- Copy orinoco fix from F-14 so it doesn't get missed.