Hi,
I am writing a small filesystem module in which currently I am trying
to implement "touch". I am able to allocate a new inode and fill the
proper information and mark the inode as dirty so that it can be
written back to disk. However before write_inode is called,
destroy_inode is getting called for the same inode number and hence it
is not getting reflected on disk. The stack trace looks like below. I
am not able to understand from where sys_close is getting called or
what might be causing this function to get called.
(gdb) bt
#0 destroy_inode (inode=0x273d3c00) at fs/inode.c:172
#1 0x080b6551 in generic_forget_inode (inode=0x273d3c00) at fs/inode.c:1080
#2 0x080b6575 in generic_drop_inode (inode=0x9006ab8) at fs/inode.c:1093
#3 0x080b65fd in iput (inode=0x273d3c00) at fs/inode.c:1116
#4 0x080b3cc5 in dentry_iput (dentry=0x26281c70) at fs/dcache.c:116
#5 0x080b3cfd in d_kill (dentry=0x26281c70) at fs/dcache.c:139
#6 0x080b3de9 in dput (dentry=0x26281c70) at fs/dcache.c:221
#7 0x080a6a29 in __fput (file=0x83625a0) at fs/file_table.c:181
#8 0x080a6918 in fput (file=0x273d3d14) at fs/file_table.c:144
#9 0x080a556a in filp_close (filp=0x83625a0, id=0x82a17d8) at fs/open.c:1106
#10 0x080a55d6 in sys_close (fd=0) at fs/open.c:1135
#11 0x0805939a in handle_syscall (r=0x82508f4) at
arch/um/kernel/skas/syscall.c:38
#12 0x0806584a in handle_trap (pid=15670, regs=0x82508f4,
local_using_sysemu=2) at arch/um/os-Linux/skas/process.c:173
#13 0x08065c41 in userspace (regs=0x82508f4) at
arch/um/os-Linux/skas/process.c:330
#14 0x08059145 in fork_handler () at arch/um/kernel/skas/process.c:96
#15 0x1f38a045 in ?? ()
Below is my create function. I am using all this in UML environment.
#define NNGFS_I(ptr) container_of(ptr,struct nngfs_inode_info,vino)
int nngfs_create(struct inode *dir, struct dentry *dentry, int mode,
struct nameidata *nd)
{
int inum=0,ret=0;
struct buffer_head *bh;
struct inode *newnip;
struct nngfs_inode *nino;
struct super_block *sb = dir->i_sb;
struct nngfs_info *nsb = (struct nngfs_info *)(sb->s_fs_info);
struct nngfs_superblock *n_sb = nsb->ngfs_sb;
//See if the entry already exists in the dir
ret = nngfs_find_entry(dir,dentry->d_name.name);
if(ret!=-1){
return ERR_PTR(-EEXIST);
}
//See the bitmap and get the inode number
inum = Get_free_inode_number(n_sb);
if(inum == -1){
return ERR_PTR(-ENOSPC);
}
//Allocate the new inode
newnip = new_inode(sb);
if(!newnip){
return ERR_PTR(-ENOSPC);
}
bh = (struct buffer_head *)(nsb->sbh);
n_sb->inode_bitmap=setbit(n_sb->inode_bitmap,inum);
newnip->i_ino = inum;
dir->i_nlink++;
newnip->i_atime = newnip->i_mtime = newnip->i_ctime = CURRENT_TIME_SEC;
newnip->i_uid = dir->i_uid;
newnip->i_gid = dir->i_gid;
if(S_ISDIR(mode)){
newnip->i_mode = NNGFS_DIR;
newnip->i_op = &nngfs_dir_inode_operations;
newnip->i_fop = &nngfs_dir_operations;
}
else{
newnip->i_mode = NNGFS_FILE;
newnip->i_op = &nngfs_file_inode_operations;
newnip->i_fop = &nngfs_file_operations;
}
nino = NNGFS_I(newnip);
nino->filetype = newnip->i_mode ;
nino->atime = nino->mtime = nino->ctime = CURRENT_TIME_SEC;
nino->uid = dir->i_uid;
nino->gid = dir->i_gid;
nino->size = 0;
nino->blockno = nino->inode+1;
nino->magic = 0xdeadbeef;
nino->inode = inum;
sb->s_dirt=1;
inode_inc_link_count(newnip);
// insert_inode_hash(newnip);
d_instantiate(dentry,newnip);
mark_buffer_dirty(bh); //Write the new bitmap to disk
mark_inode_dirty(newnip);
//Add the name information to dir entry
if(nngfs_dir_add(dir,inum,dentry->d_name.name)){
return ERR_PTR(-EMFILE);
}
mark_inode_dirty(dir);
return 0;
}
Thanks for any help/suggestions.
--
Thanks & Regards,
********************************************
Manish Katiyar ( http://mkatiyar.googlepages.com )
3rd Floor, Fair Winds Block
EGL Software Park
Off Intermediate Ring Road
Bangalore 560071, India
***********************************************
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