Carlos Maiolino:
> This V2 looks very reasonable, and fix the problem with files with inode=0 on
> tmpfs which I tested here, so, consider it
>
> Reviewed-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
Just out of curious, how did you notice the problem of inode=0? I think
it is hard for everyone to meet the problem.
And after posting the patch, some people reported me a bug related to
Sysv shm. This extra patch supports Sysv shm. But I don't like it since
it introduces an additional condition into the very normal path.
J. R. Okajima
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index ca658a8..fda816e 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -25,6 +25,7 @@ struct shmem_inode_info {
struct shmem_sb_info {
struct mutex idr_lock;
+ bool idr_nouse;
struct idr idr; /* manages inode-number */
unsigned long max_blocks; /* How many blocks are allowed */
struct percpu_counter used_blocks; /* How many are allocated */
diff --git a/mm/shmem.c b/mm/shmem.c
index 0aa3b85..5eb75e9 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -648,7 +648,7 @@ static void shmem_evict_inode(struct inode *inode)
simple_xattrs_free(&info->xattrs);
WARN_ON(inode->i_blocks);
- if (inode->i_ino) {
+ if (!sbinfo->idr_nouse && inode->i_ino) {
mutex_lock(&sbinfo->idr_lock);
idr_remove(&sbinfo->idr, inode->i_ino);
mutex_unlock(&sbinfo->idr_lock);
@@ -1423,19 +1423,24 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
break;
}
- /* inum 0 and 1 are unused */
- mutex_lock(&sbinfo->idr_lock);
- ino = idr_alloc(&sbinfo->idr, inode, 2, INT_MAX, GFP_NOFS);
- if (ino > 0) {
- inode->i_ino = ino;
- mutex_unlock(&sbinfo->idr_lock);
- __insert_inode_hash(inode, inode->i_ino);
- } else {
- inode->i_ino = 0;
- mutex_unlock(&sbinfo->idr_lock);
- iput(inode); /* shmem_free_inode() will be called */
- inode = NULL;
- }
+ if (!sbinfo->idr_nouse) {
+ /* inum 0 and 1 are unused */
+ mutex_lock(&sbinfo->idr_lock);
+ ino = idr_alloc(&sbinfo->idr, inode, 2, INT_MAX,
+ GFP_NOFS);
+ if (ino > 0) {
+ inode->i_ino = ino;
+ mutex_unlock(&sbinfo->idr_lock);
+ __insert_inode_hash(inode, inode->i_ino);
+ } else {
+ inode->i_ino = 0;
+ mutex_unlock(&sbinfo->idr_lock);
+ iput(inode);
+ /* shmem_free_inode() will be called */
+ inode = NULL;
+ }
+ } else
+ inode->i_ino = get_next_ino();
} else
shmem_free_inode(sb);
return inode;
@@ -2560,7 +2565,8 @@ static void shmem_put_super(struct super_block *sb)
{
struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
- idr_destroy(&sbinfo->idr);
+ if (!sbinfo->idr_nouse)
+ idr_destroy(&sbinfo->idr);
percpu_counter_destroy(&sbinfo->used_blocks);
mpol_put(sbinfo->mpol);
kfree(sbinfo);
@@ -2682,6 +2688,15 @@ static void shmem_destroy_inodecache(void)
kmem_cache_destroy(shmem_inode_cachep);
}
+static __init void shmem_no_idr(struct super_block *sb)
+{
+ struct shmem_sb_info *sbinfo;
+
+ sbinfo = SHMEM_SB(sb);
+ sbinfo->idr_nouse = true;
+ idr_destroy(&sbinfo->idr);
+}
+
static const struct address_space_operations shmem_aops = {
.writepage = shmem_writepage,
.set_page_dirty = __set_page_dirty_no_writeback,
@@ -2814,6 +2829,7 @@ int __init shmem_init(void)
printk(KERN_ERR "Could not kern_mount tmpfs\n");
goto out1;
}
+ shmem_no_idr(shm_mnt->mnt_sb);
return 0;
out1:
--
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