Libguestfs - Jan 2015 - [PATCH 2/2] sparsify: ignore read-only devices

In copy mode, make sure to not zero-free-space read-only btrfs
snapshots, as we cannot write to them.
---
 sparsify/copying.ml | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/sparsify/copying.ml b/sparsify/copying.ml
index 8d77964..4c23939 100644
--- a/sparsify/copying.ml
+++ b/sparsify/copying.ml
@@ -208,6 +208,11 @@ You can ignore this warning or change it to a hard failure
using the
    * and selected swap partitions.
    *)
   let filesystems = g#list_filesystems () in
+  let btrfs_filesystems = List.filter (
+    fun (fs, fstype) ->
+      fstype = "btrfs"
+  ) filesystems in
+  let btrfs_filesystems = List.map fst btrfs_filesystems in
   let filesystems = List.map fst filesystems in
   let filesystems = List.sort compare filesystems in
 
@@ -216,6 +221,18 @@ You can ignore this warning or change it to a hard failure
using the
     List.exists (fun fs' -> fs = g#canonical_device_name fs')
ignores
   in
 
+  let is_readonly_btrfs_snapshot fs mp +    try
+      let is_btrfs = List.mem fs btrfs_filesystems in
+      if is_btrfs then (
+        try
+          let vol_info = g#btrfs_subvolume_show mp in
+          string_find (List.assoc "Flags" vol_info)
"readonly" <> -1
+        with _ -> false
+      ) else false
+    with Not_found -> false
+  in
+
   List.iter (
     fun fs ->
       if not (is_ignored fs) then (
@@ -230,10 +247,15 @@ You can ignore this warning or change it to a hard failure
using the
             with _ -> false in
 
           if mounted then (
-            if not quiet then
-              printf (f_"Fill free space in %s with zero ...\n%!")
fs;
+            if is_readonly_btrfs_snapshot fs "/" then (
+              if not quiet then
+                printf (f_"Skipping %s, as it is a read-only btrfs
snapshot.\n%!") fs;
+            ) else (
+              if not quiet then
+                printf (f_"Fill free space in %s with zero ...\n%!")
fs;
 
-            g#zero_free_space "/"
+              g#zero_free_space "/"
+            )
           ) else (
             let is_linux_x86_swap                (* Look for the signature for
Linux swap on i386.
-- 
1.9.3

In copy mode, make sure to not zero-free-space devices mounted as
read-only, as we cannot write to them.

Related to RHBZ#1079625.
---
 sparsify/copying.ml | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/sparsify/copying.ml b/sparsify/copying.ml
index 4c23939..9c2c545 100644
--- a/sparsify/copying.ml
+++ b/sparsify/copying.ml
@@ -233,6 +233,13 @@ You can ignore this warning or change it to a hard failure
using the
     with Not_found -> false
   in
 
+  let is_readonly_device mp +    let statvfs = g#statvfs mp in
+    let flags = statvfs.G.flag in
+    (* 0x01 is ST_RDONLY in Linux' GNU libc. *)
+    flags <> -1_L && (flags &^ 0x1_L) <> 0_L
+  in
+
   List.iter (
     fun fs ->
       if not (is_ignored fs) then (
@@ -250,6 +257,9 @@ You can ignore this warning or change it to a hard failure
using the
             if is_readonly_btrfs_snapshot fs "/" then (
               if not quiet then
                 printf (f_"Skipping %s, as it is a read-only btrfs
snapshot.\n%!") fs;
+            ) else if is_readonly_device "/" then (
+              if not quiet then
+                printf (f_"Skipping %s, as it is a read-only
device.\n%!") fs;
             ) else (
               if not quiet then
                 printf (f_"Fill free space in %s with zero ...\n%!")
fs;
-- 
1.9.3

On Thu, Jan 29, 2015 at 06:54:30PM +0100, Pino Toscano
wrote:
> +  let is_readonly_btrfs_snapshot fs mp > +    try
> +      let is_btrfs = List.mem fs btrfs_filesystems in
> +      if is_btrfs then (
> +        try
> +          let vol_info = g#btrfs_subvolume_show mp in
> +          string_find (List.assoc "Flags" vol_info)
"readonly" <> -1
> +        with _ -> false
Hmm, catching every exception and ignoring it?  I'm guessing you're
trying to ignore G.Error only here (Not_found could escape but will be
caught by the outer try).
> +      ) else false
> +    with Not_found -> false
> +  in
Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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On Thu, Jan 29, 2015 at 06:54:31PM +0100, Pino Toscano
wrote:
> In copy mode, make sure to not zero-free-space devices mounted as
> read-only, as we cannot write to them.
> 
> Related to RHBZ#1079625.
> ---
>  sparsify/copying.ml | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/sparsify/copying.ml b/sparsify/copying.ml
> index 4c23939..9c2c545 100644
> --- a/sparsify/copying.ml
> +++ b/sparsify/copying.ml
> @@ -233,6 +233,13 @@ You can ignore this warning or change it to a hard
failure using the
>      with Not_found -> false
>    in
>  
> +  let is_readonly_device mp > +    let statvfs = g#statvfs mp in
> +    let flags = statvfs.G.flag in
> +    (* 0x01 is ST_RDONLY in Linux' GNU libc. *)
> +    flags <> -1_L && (flags &^ 0x1_L) <> 0_L
> +  in
> +
>    List.iter (
>      fun fs ->
>        if not (is_ignored fs) then (
> @@ -250,6 +257,9 @@ You can ignore this warning or change it to a hard
failure using the
>              if is_readonly_btrfs_snapshot fs "/" then (
>                if not quiet then
>                  printf (f_"Skipping %s, as it is a read-only btrfs
snapshot.\n%!") fs;
> +            ) else if is_readonly_device "/" then (
> +              if not quiet then
> +                printf (f_"Skipping %s, as it is a read-only
device.\n%!") fs;
>              ) else (
>                if not quiet then
>                  printf (f_"Fill free space in %s with zero
...\n%!") fs;
Looks good, ACK.

Rich.

-- 
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Read my programming and virtualization blog: http://rwmj.wordpress.com
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