github/containerd
4
0
Fork 0
Code Issues Pull Requests Packages Projects Releases 2 Wiki Activity

strip-volatile-option-tmp-mounts

Browse Source 
Signed-off-by: krglosse <krglosse@us.ibm.com>

do not alter original slice

Signed-off-by: krglosse <krglosse@us.ibm.com>

Update core/mount/temp.go

makes sense, thank you!

Co-authored-by: Derek McGowan <derek@mcg.dev>
Signed-off-by: KodieGlosserIBM <39170759+KodieGlosserIBM@users.noreply.github.com>

do not copy mount structure unless conditional is met and adding a test case for it

Signed-off-by: krglosse <krglosse@us.ibm.com>

copy option slice when removing the element instead of giving the element an empty string

remove unneeded block

Signed-off-by: krglosse <krglosse@us.ibm.com>

simplify

Signed-off-by: krglosse <krglosse@us.ibm.com>
This commit is contained in:
krglosse
2024-01-10 12:43:32 -06:00
parent 02e0fef84b
commit cfe8321b4c
2 changed files with 150 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
core/mount/temp.go
View File

@@ -28,6 +28,7 @@ var tempMountLocation = getTempDir()
// WithTempMount mounts the provided mounts to a temp dir, and pass the temp dir to f.
// The mounts are valid during the call to the f.
// The volatile option of overlayfs doesn't allow to mount again using the same upper / work dirs. Since it's a temp mount, avoid using that option here if found.
// Finally we will unmount and remove the temp dir regardless of the result of f.
func WithTempMount(ctx context.Context, mounts []Mount, f func(root string) error) (err error) {
root, uerr := os.MkdirTemp(tempMountLocation, "containerd-mount")
@@ -58,7 +59,8 @@ func WithTempMount(ctx context.Context, mounts []Mount, f func(root string) erro
}
}
}()
if uerr = All(mounts, root); uerr != nil {
if uerr = All(removeVolatileTempMount(mounts), root); uerr != nil {
return fmt.Errorf("failed to mount %s: %w", root, uerr)
}
if err := f(root); err != nil {
@@ -67,6 +69,42 @@ func WithTempMount(ctx context.Context, mounts []Mount, f func(root string) erro
return nil
}
// removeVolatileTempMount The volatile option of overlayfs doesn't allow to mount again using the
// same upper / work dirs. Since it's a temp mount, avoid using that
// option here. Reference: https://docs.kernel.org/filesystems/overlayfs.html#volatile-mount
// TODO: Make this logic conditional once the kernel supports reusing
// overlayfs volatile mounts.
func removeVolatileTempMount(mounts []Mount) []Mount {
var out []Mount
for i, m := range mounts {
if m.Type != "overlay" {
continue
}
for j, opt := range m.Options {
if opt == "volatile" {
if out == nil {
out = copyMounts(mounts)
}
out[i].Options = append(out[i].Options[:j], out[i].Options[j+1:]...)
break
}
}
}
if out != nil {
return out
}
return mounts
}
// copyMounts creates a copy of the original slice to allow for modification and not altering the original
func copyMounts(in []Mount) []Mount {
out := make([]Mount, len(in))
copy(out, in)
return out
}
// WithReadonlyTempMount mounts the provided mounts to a temp dir as readonly,
// and pass the temp dir to f. The mounts are valid during the call to the f.
// Finally we will unmount and remove the temp dir regardless of the result of f.