minix/servers/mfs/open.c
Ben Gras bd3cde4571 Move primary cache code to libminixfs.
Add primary cache management feature to libminixfs as mfs and ext2
currently do separately, remove cache code from mfs and ext2, and make
them use the libminixfs interface. This makes all fields of the buf
struct private to libminixfs and FS clients aren't supposed to access
them at all. Only the opaque 'void *data' field (the FS block contents,
used to be called bp) is to be accessed by the FS client.

The main purpose is to implement the interface to the 2ndary vm cache
just once, get rid of some code duplication, and add a little
abstraction to reduce the code inertia of the whole caching business.

Some minor sanity checking and prohibition done by mfs in this code
as removed from the generic primary cache code as a result:
        - checking all inodes are not in use when allocating/resizing
          the cache
        - checking readonly filesystems aren't written to
        - checking the superblock isn't written to on mounted filesystems

The minixfslib code relies on fs_blockstats() in the client filesystem to
return some FS usage information.
2012-10-23 19:48:38 +02:00

333 lines
11 KiB
C

#include "fs.h"
#include <sys/stat.h>
#include <string.h>
#include <minix/com.h>
#include "buf.h"
#include "inode.h"
#include "super.h"
#include <minix/vfsif.h>
static struct inode *new_node(struct inode *ldirp, char *string, mode_t
bits, zone_t z0);
/*===========================================================================*
* fs_create *
*===========================================================================*/
int fs_create()
{
size_t len;
int r;
struct inode *ldirp;
struct inode *rip;
mode_t omode;
char lastc[MFS_NAME_MAX];
/* Read request message */
omode = (mode_t) fs_m_in.REQ_MODE;
caller_uid = (uid_t) fs_m_in.REQ_UID;
caller_gid = (gid_t) fs_m_in.REQ_GID;
/* Try to make the file. */
/* Copy the last component (i.e., file name) */
len = min( (unsigned) fs_m_in.REQ_PATH_LEN, sizeof(lastc));
err_code = sys_safecopyfrom(VFS_PROC_NR, (cp_grant_id_t) fs_m_in.REQ_GRANT,
(vir_bytes) 0, (vir_bytes) lastc, len);
if (err_code != OK) return err_code;
NUL(lastc, len, sizeof(lastc));
/* Get last directory inode (i.e., directory that will hold the new inode) */
if ((ldirp = get_inode(fs_dev, (ino_t) fs_m_in.REQ_INODE_NR)) == NULL)
return(ENOENT);
/* Create a new inode by calling new_node(). */
rip = new_node(ldirp, lastc, omode, NO_ZONE);
r = err_code;
/* If an error occurred, release inode. */
if (r != OK) {
put_inode(ldirp);
put_inode(rip);
return(r);
}
/* Reply message */
fs_m_out.RES_INODE_NR = rip->i_num;
fs_m_out.RES_MODE = rip->i_mode;
fs_m_out.RES_FILE_SIZE_LO = rip->i_size;
/* These values are needed for the execution */
fs_m_out.RES_UID = rip->i_uid;
fs_m_out.RES_GID = rip->i_gid;
/* Drop parent dir */
put_inode(ldirp);
return(OK);
}
/*===========================================================================*
* fs_mknod *
*===========================================================================*/
int fs_mknod()
{
struct inode *ip, *ldirp;
char lastc[MFS_NAME_MAX];
phys_bytes len;
/* Copy the last component and set up caller's user and group id */
len = min( (unsigned) fs_m_in.REQ_PATH_LEN, sizeof(lastc));
err_code = sys_safecopyfrom(VFS_PROC_NR, (cp_grant_id_t) fs_m_in.REQ_GRANT,
(vir_bytes) 0, (vir_bytes) lastc, (size_t) len);
if (err_code != OK) return err_code;
NUL(lastc, len, sizeof(lastc));
caller_uid = (uid_t) fs_m_in.REQ_UID;
caller_gid = (gid_t) fs_m_in.REQ_GID;
/* Get last directory inode */
if((ldirp = get_inode(fs_dev, (ino_t) fs_m_in.REQ_INODE_NR)) == NULL)
return(ENOENT);
/* Try to create the new node */
ip = new_node(ldirp, lastc, (mode_t) fs_m_in.REQ_MODE,
(zone_t) fs_m_in.REQ_DEV);
put_inode(ip);
put_inode(ldirp);
return(err_code);
}
/*===========================================================================*
* fs_mkdir *
*===========================================================================*/
int fs_mkdir()
{
int r1, r2; /* status codes */
ino_t dot, dotdot; /* inode numbers for . and .. */
struct inode *rip, *ldirp;
char lastc[MFS_NAME_MAX]; /* last component */
phys_bytes len;
/* Copy the last component and set up caller's user and group id */
len = min( (unsigned) fs_m_in.REQ_PATH_LEN, sizeof(lastc));
err_code = sys_safecopyfrom(VFS_PROC_NR, (cp_grant_id_t) fs_m_in.REQ_GRANT,
(vir_bytes) 0, (vir_bytes) lastc, (size_t) len);
if(err_code != OK) return(err_code);
NUL(lastc, len, sizeof(lastc));
caller_uid = (uid_t) fs_m_in.REQ_UID;
caller_gid = (gid_t) fs_m_in.REQ_GID;
/* Get last directory inode */
if((ldirp = get_inode(fs_dev, (ino_t) fs_m_in.REQ_INODE_NR)) == NULL)
return(ENOENT);
/* Next make the inode. If that fails, return error code. */
rip = new_node(ldirp, lastc, (mode_t) fs_m_in.REQ_MODE, (zone_t) 0);
if(rip == NULL || err_code == EEXIST) {
put_inode(rip); /* can't make dir: it already exists */
put_inode(ldirp);
return(err_code);
}
/* Get the inode numbers for . and .. to enter in the directory. */
dotdot = ldirp->i_num; /* parent's inode number */
dot = rip->i_num; /* inode number of the new dir itself */
/* Now make dir entries for . and .. unless the disk is completely full. */
/* Use dot1 and dot2, so the mode of the directory isn't important. */
rip->i_mode = (mode_t) fs_m_in.REQ_MODE; /* set mode */
r1 = search_dir(rip, dot1, &dot, ENTER, IGN_PERM);/* enter . in the new dir*/
r2 = search_dir(rip, dot2, &dotdot, ENTER, IGN_PERM); /* enter .. in the new
dir */
/* If both . and .. were successfully entered, increment the link counts. */
if (r1 == OK && r2 == OK) {
/* Normal case. It was possible to enter . and .. in the new dir. */
rip->i_nlinks++; /* this accounts for . */
ldirp->i_nlinks++; /* this accounts for .. */
IN_MARKDIRTY(ldirp); /* mark parent's inode as dirty */
} else {
/* It was not possible to enter . or .. probably disk was full -
* links counts haven't been touched. */
if(search_dir(ldirp, lastc, NULL, DELETE, IGN_PERM) != OK)
panic("Dir disappeared: %ul", rip->i_num);
rip->i_nlinks--; /* undo the increment done in new_node() */
}
IN_MARKDIRTY(rip); /* either way, i_nlinks has changed */
put_inode(ldirp); /* return the inode of the parent dir */
put_inode(rip); /* return the inode of the newly made dir */
return(err_code); /* new_node() always sets 'err_code' */
}
/*===========================================================================*
* fs_slink *
*===========================================================================*/
int fs_slink()
{
phys_bytes len;
struct inode *sip; /* inode containing symbolic link */
struct inode *ldirp; /* directory containing link */
register int r; /* error code */
char string[MFS_NAME_MAX]; /* last component of the new dir's path name */
struct buf *bp; /* disk buffer for link */
caller_uid = (uid_t) fs_m_in.REQ_UID;
caller_gid = (gid_t) fs_m_in.REQ_GID;
/* Copy the link name's last component */
len = min( (unsigned) fs_m_in.REQ_PATH_LEN, sizeof(string));
r = sys_safecopyfrom(VFS_PROC_NR, (cp_grant_id_t) fs_m_in.REQ_GRANT,
(vir_bytes) 0, (vir_bytes) string, (size_t) len);
if (r != OK) return(r);
NUL(string, len, sizeof(string));
/* Temporarily open the dir. */
if( (ldirp = get_inode(fs_dev, (ino_t) fs_m_in.REQ_INODE_NR)) == NULL)
return(EINVAL);
/* Create the inode for the symlink. */
sip = new_node(ldirp, string, (mode_t) (I_SYMBOLIC_LINK | RWX_MODES),
(zone_t) 0);
/* Allocate a disk block for the contents of the symlink.
* Copy contents of symlink (the name pointed to) into first disk block. */
if( (r = err_code) == OK) {
bp = new_block(sip, (off_t) 0);
if (bp == NULL)
r = err_code;
else
r = sys_safecopyfrom(VFS_PROC_NR,
(cp_grant_id_t) fs_m_in.REQ_GRANT3,
(vir_bytes) 0, (vir_bytes) b_data(bp),
(size_t) fs_m_in.REQ_MEM_SIZE);
if(bp != NULL && r == OK) {
b_data(bp)[_MIN_BLOCK_SIZE-1] = '\0';
sip->i_size = (off_t) strlen(b_data(bp));
if(sip->i_size != fs_m_in.REQ_MEM_SIZE) {
/* This can happen if the user provides a buffer
* with a \0 in it. This can cause a lot of trouble
* when the symlink is used later. We could just use
* the strlen() value, but we want to let the user
* know he did something wrong. ENAMETOOLONG doesn't
* exactly describe the error, but there is no
* ENAMETOOWRONG.
*/
r = ENAMETOOLONG;
}
}
put_block(bp, DIRECTORY_BLOCK); /* put_block() accepts NULL. */
if(r != OK) {
sip->i_nlinks = NO_LINK;
if(search_dir(ldirp, string, NULL, DELETE, IGN_PERM) != OK)
panic("Symbolic link vanished");
}
}
/* put_inode() accepts NULL as a noop, so the below are safe. */
put_inode(sip);
put_inode(ldirp);
return(r);
}
/*===========================================================================*
* new_node *
*===========================================================================*/
static struct inode *new_node(struct inode *ldirp,
char *string, mode_t bits, zone_t z0)
{
/* New_node() is called by fs_open(), fs_mknod(), and fs_mkdir().
* In all cases it allocates a new inode, makes a directory entry for it in
* the ldirp directory with string name, and initializes it.
* It returns a pointer to the inode if it can do this;
* otherwise it returns NULL. It always sets 'err_code'
* to an appropriate value (OK or an error code).
*
* The parsed path rest is returned in 'parsed' if parsed is nonzero. It
* has to hold at least MFS_NAME_MAX bytes.
*/
register struct inode *rip;
register int r;
if (ldirp->i_nlinks == NO_LINK) { /* Dir does not actually exist */
err_code = ENOENT;
return(NULL);
}
/* Get final component of the path. */
rip = advance(ldirp, string, IGN_PERM);
if (S_ISDIR(bits) && (ldirp->i_nlinks >= LINK_MAX)) {
/* New entry is a directory, alas we can't give it a ".." */
put_inode(rip);
err_code = EMLINK;
return(NULL);
}
if ( rip == NULL && err_code == ENOENT) {
/* Last path component does not exist. Make new directory entry. */
if ( (rip = alloc_inode((ldirp)->i_dev, bits)) == NULL) {
/* Can't creat new inode: out of inodes. */
return(NULL);
}
/* Force inode to the disk before making directory entry to make
* the system more robust in the face of a crash: an inode with
* no directory entry is much better than the opposite.
*/
rip->i_nlinks++;
rip->i_zone[0] = z0; /* major/minor device numbers */
rw_inode(rip, WRITING); /* force inode to disk now */
/* New inode acquired. Try to make directory entry. */
if((r=search_dir(ldirp, string, &rip->i_num, ENTER, IGN_PERM)) != OK) {
rip->i_nlinks--; /* pity, have to free disk inode */
IN_MARKDIRTY(rip); /* dirty inodes are written out */
put_inode(rip); /* this call frees the inode */
err_code = r;
return(NULL);
}
} else if (err_code == EENTERMOUNT || err_code == ELEAVEMOUNT) {
r = EEXIST;
} else {
/* Either last component exists, or there is some problem. */
if (rip != NULL)
r = EEXIST;
else
r = err_code;
}
/* The caller has to return the directory inode (*ldirp). */
err_code = r;
return(rip);
}
/*===========================================================================*
* fs_inhibread *
*===========================================================================*/
int fs_inhibread()
{
struct inode *rip;
if((rip = find_inode(fs_dev, (ino_t) fs_m_in.REQ_INODE_NR)) == NULL)
return(EINVAL);
/* inhibit read ahead */
rip->i_seek = ISEEK;
return(OK);
}