 fd      .  
  fd array.       NR OPEN DEFAULT
 32,    32  .    -
 32  ,         fd
  .        
  ,       .
 ,       ,  -
   .       -
 32 ,      
    NR_OPEN_DE FAULT   
.   ,   ,   -
 fs_struct,   ,   ,   -
   fs  .     <
<linux/fs_struct ,h>       .

struct fs_struct {

atomic_t       count;    /*     */
rwlock t       lock;     /*     */
int            umask;    /*    , 

  */
struct dentry   *root;    /*  dentry   */
struct dentry   *pwd;     /*  dentry    */
struct dentry   *altroot; /*  dentry   */
struct vfsmount *rootmnt; /*     */
struct vfsmount *pwdmnt; /*    */
struct vfsmount *altrootmnt; /*   */

};

         
.

,  ,    namespace,  
  <linux/namespace .h>       namespace
 .  ,    ,
    Linux  2.4.      -
      .  -
,        ,   
    ,   . 
,       .

struct namespace (

atomic t           count;  /*     */
struct vfsmount     *root;   /*     */
struct list head    list;    /*    */
struct rw_semaphore sem;     /*  -    */

};

 list      
,    .

        -
 .         -
  fiies_struct   fs_struct.   ,

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