Hi,
Finally I could figure out the problem. write_inode was not getting
called because I had a call to inode_inc_link_count() in my create
function. Once I remove it the function gets called and the changes
done are also reflected on the disk.
But the question is why is this call affecting the behaviour. All I
can see in this function is that it is incrementing the link count of
the vfs inode and marking it as dirty and so I see no reason to change
the behaviour.
Gurus any help/pointers appreciated. Thanks in advance
On Jan 26, 2008 12:47 AM, Manish Katiyar <mkatiyar@xxxxxxxxx> wrote:
> 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
> ***********************************************
>
--
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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