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It can be accessed and reviewed at: https://github.com/lxc/lxd/pull/3021
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=== Description (from pull-request) ===
From 92a386c356dcaa9e31efd3aa7ebd92b311477079 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brau...@ubuntu.com>
Date: Sun, 5 Mar 2017 13:25:05 +0100
Subject: [PATCH 1/2] btrfs: correctly handle loop-backed pools
We allow users to create loop-backed btrfs pools even it they are on a btrfs
filesystem already. However, until recently StoragePoolMount() did not correctly
handle this case. This commit ensure that mounting a loop-backed storage pool on
a btrfs filesystem works correctly.
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
---
lxd/storage_btrfs.go | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/lxd/storage_btrfs.go b/lxd/storage_btrfs.go
index d1b3b1d..eb77824 100644
--- a/lxd/storage_btrfs.go
+++ b/lxd/storage_btrfs.go
@@ -341,8 +341,13 @@ func (s *storageBtrfs) StoragePoolMount() (bool, error) {
}
mountSource := source
+ isBlockDev := shared.IsBlockdevPath(source)
if filepath.IsAbs(source) {
- if !shared.IsBlockdevPath(source) && s.d.BackingFs != "btrfs" {
+ loopFilePath := shared.VarPath("disks", s.pool.Name+".img")
+ if !isBlockDev && source == loopFilePath {
+ // If source == "${LXD_DIR}"/disks/{pool_name} it is a
+ // loop file we're dealing with.
+ //
// Since we mount the loop device LO_FLAGS_AUTOCLEAR is
// fine since the loop device will be kept around for as
// long as the mount exists.
@@ -352,9 +357,11 @@ func (s *storageBtrfs) StoragePoolMount() (bool, error) {
}
mountSource = loopF.Name()
defer loopF.Close()
- } else {
+ } else if !isBlockDev && s.d.BackingFs == "btrfs" {
+ // User is using btrfs subvolume as pool.
return false, nil
}
+ // User is using block device path.
} else {
// Try to lookup the disk device by UUID but don't fail. If we
// don't find one this might just mean we have been given the
From ab64dd7aa13d26e11ae18019925bdaf07bf468f7 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brau...@ubuntu.com>
Date: Sun, 5 Mar 2017 20:02:33 +0100
Subject: [PATCH 2/2] btrfs: handle custom subvolume paths
This improves handling:
1. lxc storage create pool1 source=/path/to/subvolume
- create /path/to/subvolume if it doesn't already exist and bind-mount onto
${LXD_DIR}/storage-pools/pool1
2. lxc storage create pool1 source=${LXD_DIR}/storage-pools/pool1
- create subvolume if LXD is located on btrfs
3. lxc storage create pool1
source=/path-somewhere-under-${LXD_DIR}-but-not-under-storage-pools-subdir
- This is considered invalid (As it might mess with LXD's on-disk layout).
The following error message is given:
chb@conventiont|~/source/go/src/github.com/lxc/lxd|2017-03-05/btrfs_improvements
*$%>
> lxc storage create pool1 btrfs source=/home/chb/mnt/l1/storage-pools/
error: BTRFS subvolumes requests in LXD directory "/home/chb/mnt/l1"
are only valid under "/home/chb/mnt/l1/storage-pools"
(e.g. source=/home/chb/mnt/l1/storage-pools/pool1)
I really wouldn't want to allow users to create subvolumes under say e.g.
${LXD_DIR}/containers or the like. This will just cause trouble.
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
---
lxd/storage_btrfs.go | 76 +++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 57 insertions(+), 19 deletions(-)
diff --git a/lxd/storage_btrfs.go b/lxd/storage_btrfs.go
index eb77824..c563c47 100644
--- a/lxd/storage_btrfs.go
+++ b/lxd/storage_btrfs.go
@@ -138,13 +138,32 @@ func (s *storageBtrfs) StoragePoolCreate() error {
return fmt.Errorf("Failed to create the
BTRFS pool: %s", output)
}
} else {
- if isBtrfsSubVolume(source) || s.d.BackingFs ==
"btrfs" {
+ if isBtrfsSubVolume(source) {
+ subvols, err :=
btrfsSubVolumesGet(source)
+ if err != nil {
+ return fmt.Errorf("Could not
determine if existing BTRFS subvolume ist empty: %s.", err)
+ }
+ if len(subvols) > 0 {
+ return fmt.Errorf("Requested
BTRFS subvolume exists but is not empty.")
+ }
+ } else {
+ cleanSource := filepath.Clean(source)
+ lxdDir := shared.VarPath()
+ poolMntPoint :=
getStoragePoolMountPoint(s.pool.Name)
+ if shared.PathExists(source) &&
!isOnBtrfs(source) {
+ return fmt.Errorf("Existing
path is neither a BTRFS subvolume nor does it reside on a BTRFS filesystem.")
+ } else if
strings.HasPrefix(cleanSource, lxdDir) {
+ if cleanSource != poolMntPoint {
+ return
fmt.Errorf("BTRFS subvolumes requests in LXD directory \"%s\" are only valid
under \"%s\"\n(e.g. source=%s)", shared.VarPath(),
shared.VarPath("storage-pools"), poolMntPoint)
+ } else if s.d.BackingFs !=
"btrfs" {
+ return
fmt.Errorf("Creation of BTRFS subvolume requested but \"%s\" does not reside on
BTRFS filesystem.", source)
+ }
+ }
+
err := btrfsSubVolumeCreate(source)
if err != nil {
return err
}
- } else {
- return fmt.Errorf("Custom loop file
locations are not supported.")
}
}
} else {
@@ -274,11 +293,14 @@ func (s *storageBtrfs) StoragePoolDelete() error {
shared.LogDebugf(msg)
} else {
var err error
- if s.d.BackingFs == "btrfs" {
- err = btrfsSubVolumesDelete(source)
- } else {
+ cleanSource := filepath.Clean(source)
+ sourcePath := shared.VarPath("disks", s.pool.Name)
+ loopFilePath := sourcePath + ".img"
+ if cleanSource == loopFilePath {
// This is a loop file --> simply remove it.
err = os.Remove(source)
+ } else {
+ err = btrfsSubVolumesDelete(source)
}
if err != nil {
return err
@@ -340,9 +362,12 @@ func (s *storageBtrfs) StoragePoolMount() (bool, error) {
return false, nil
}
+ mountFlags := uintptr(0)
mountSource := source
isBlockDev := shared.IsBlockdevPath(source)
if filepath.IsAbs(source) {
+ cleanSource := filepath.Clean(source)
+ poolMntPoint := getStoragePoolMountPoint(s.pool.Name)
loopFilePath := shared.VarPath("disks", s.pool.Name+".img")
if !isBlockDev && source == loopFilePath {
// If source == "${LXD_DIR}"/disks/{pool_name} it is a
@@ -357,8 +382,10 @@ func (s *storageBtrfs) StoragePoolMount() (bool, error) {
}
mountSource = loopF.Name()
defer loopF.Close()
- } else if !isBlockDev && s.d.BackingFs == "btrfs" {
- // User is using btrfs subvolume as pool.
+ } else if !isBlockDev && cleanSource != poolMntPoint {
+ mountSource = source
+ mountFlags = syscall.MS_BIND
+ } else if !isBlockDev && cleanSource == poolMntPoint &&
s.d.BackingFs == "btrfs" {
return false, nil
}
// User is using block device path.
@@ -382,7 +409,7 @@ func (s *storageBtrfs) StoragePoolMount() (bool, error) {
}
// This is a block device.
- err := syscall.Mount(mountSource, poolMntPoint, "btrfs", 0,
btrfsMntOptions)
+ err := syscall.Mount(mountSource, poolMntPoint, "btrfs", mountFlags,
btrfsMntOptions)
if err != nil {
return false, err
}
@@ -1313,7 +1340,8 @@ func (s *storageBtrfs) ImageUmount(fingerprint string)
(bool, error) {
func btrfsSubVolumeCreate(subvol string) error {
parentDestPath := filepath.Dir(subvol)
if !shared.PathExists(parentDestPath) {
- if err := os.MkdirAll(parentDestPath, 0711); err != nil {
+ err := os.MkdirAll(parentDestPath, 0711)
+ if err != nil {
return err
}
}
@@ -1324,11 +1352,8 @@ func btrfsSubVolumeCreate(subvol string) error {
"create",
subvol).CombinedOutput()
if err != nil {
- return fmt.Errorf(
- "btrfs subvolume create failed, subvol=%s, output%s",
- subvol,
- string(output),
- )
+ shared.LogErrorf("Failed to create BTRFS subvolume \"%s\":
%s.", subvol, string(output))
+ return err
}
return nil
@@ -1526,10 +1551,8 @@ func (s *storageBtrfs) btrfsPoolVolumesSnapshot(source
string, dest string, read
return nil
}
-/*
- * isBtrfsSubVolume returns true if the given Path is a btrfs subvolume
- * else false.
- */
+// isBtrfsSubVolume returns true if the given Path is a btrfs subvolume else
+// false.
func isBtrfsSubVolume(subvolPath string) bool {
fs := syscall.Stat_t{}
err := syscall.Lstat(subvolPath, &fs)
@@ -1545,6 +1568,21 @@ func isBtrfsSubVolume(subvolPath string) bool {
return true
}
+func isOnBtrfs(path string) bool {
+ fs := syscall.Statfs_t{}
+
+ err := syscall.Statfs(path, &fs)
+ if err != nil {
+ return false
+ }
+
+ if fs.Type != filesystemSuperMagicBtrfs {
+ return false
+ }
+
+ return true
+}
+
func btrfsSubVolumesGet(path string) ([]string, error) {
result := []string{}
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