The existing ctx->vfsroot is dangerous. We take it from
the root task via: ctx->root_task->fs->root and don't take
a ref on the 'fs' in there. We also take a ref on the
fs.root which is worthless.
So, replace ctx->vfsroot with a reference to the 'fs'
instead. This gives us easy access to fs.root later on,
and also lets us do proper refcounting.
This, of course, eventually needs to be done per-process
but this should at least remove a potential oops.
---
linux-2.6.git-dave/checkpoint/checkpoint.c | 7 ++-----
linux-2.6.git-dave/checkpoint/ckpt_file.c | 2 +-
linux-2.6.git-dave/checkpoint/ckpt_mem.c | 2 +-
linux-2.6.git-dave/checkpoint/sys.c | 4 ++--
linux-2.6.git-dave/include/linux/checkpoint.h | 2 +-
5 files changed, 7 insertions(+), 10 deletions(-)
diff -puN checkpoint/checkpoint.c~fix-cr_ctx_checkpoint-locking
checkpoint/checkpoint.c
--- linux-2.6.git/checkpoint/checkpoint.c~fix-cr_ctx_checkpoint-locking
2008-12-02 10:21:52.000000000 -0800
+++ linux-2.6.git-dave/checkpoint/checkpoint.c 2008-12-02 10:21:52.000000000
-0800
@@ -511,12 +511,9 @@ static int cr_ctx_checkpoint(struct cr_c
* assume checkpointer is in container's root vfs
* FIXME: this works for now, but will change with real containers
*/
- task_lock(ctx->root_task);
- ctx->vfsroot = &ctx->root_task->fs->root;
- task_unlock(ctx->root_task);
- if (!ctx->vfsroot)
+ ctx->fs = get_fs_struct(ctx->root_task);
+ if (!ctx->fs)
return -EAGAIN;
- path_get(ctx->vfsroot);
return 0;
}
diff -puN checkpoint/ckpt_file.c~fix-cr_ctx_checkpoint-locking
checkpoint/ckpt_file.c
--- linux-2.6.git/checkpoint/ckpt_file.c~fix-cr_ctx_checkpoint-locking
2008-12-02 10:21:52.000000000 -0800
+++ linux-2.6.git-dave/checkpoint/ckpt_file.c 2008-12-02 10:46:56.000000000
-0800
@@ -117,7 +117,7 @@ static int cr_write_fd_data(struct cr_ct
if (ret < 0)
return ret;
- return cr_write_fname(ctx, &file->f_path, ctx->vfsroot);
+ return cr_write_fname(ctx, &file->f_path, &ctx->fs.root);
}
/**
diff -puN checkpoint/ckpt_mem.c~fix-cr_ctx_checkpoint-locking
checkpoint/ckpt_mem.c
--- linux-2.6.git/checkpoint/ckpt_mem.c~fix-cr_ctx_checkpoint-locking
2008-12-02 10:21:52.000000000 -0800
+++ linux-2.6.git-dave/checkpoint/ckpt_mem.c 2008-12-02 10:21:52.000000000
-0800
@@ -436,7 +436,7 @@ static int cr_write_vma(struct cr_ctx *c
/* save the file name, if relevant */
if (vma->vm_file) {
- ret = cr_write_fname(ctx, &vma->vm_file->f_path, ctx->vfsroot);
+ ret = cr_write_fname(ctx, &vma->vm_file->f_path, &ctx->fs.root);
if (ret < 0)
return ret;
}
diff -puN checkpoint/sys.c~fix-cr_ctx_checkpoint-locking checkpoint/sys.c
--- linux-2.6.git/checkpoint/sys.c~fix-cr_ctx_checkpoint-locking
2008-12-02 10:21:52.000000000 -0800
+++ linux-2.6.git-dave/checkpoint/sys.c 2008-12-02 10:21:52.000000000 -0800
@@ -152,8 +152,8 @@ static void cr_ctx_free(struct cr_ctx *c
kfree(ctx->hbuf);
- if (ctx->vfsroot)
- path_put(ctx->vfsroot);
+ if (ctx->fs)
+ put_fs_struct(ctx->fs);
cr_pgarr_free(ctx);
cr_objhash_free(ctx);
diff -puN include/linux/checkpoint.h~fix-cr_ctx_checkpoint-locking
include/linux/checkpoint.h
--- linux-2.6.git/include/linux/checkpoint.h~fix-cr_ctx_checkpoint-locking
2008-12-02 10:21:52.000000000 -0800
+++ linux-2.6.git-dave/include/linux/checkpoint.h 2008-12-02
10:21:52.000000000 -0800
@@ -41,7 +41,7 @@ struct cr_ctx {
struct list_head pgarr_list; /* page array to dump VMA contents */
- struct path *vfsroot; /* container root (FIXME) */
+ struct fs_struct *fs; /* container root/pwd (FIXME) */
/* [multi-process checkpoint] */
struct task_struct **tasks_arr; /* array of all tasks [checkpoint] */
_
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