[PATCH 03/16 v5] pramfs: inode operations

[Marco Stornelli]

From: Marco Stornelli <marco.stornelli@xxxxxxxxx>

Inode methods (allocate/free/read/write).

Signed-off-by: Marco Stornelli <marco.stornelli@xxxxxxxxx>
---
diff -Nurp linux-2.6.36-orig/fs/pramfs/inode.c linux-2.6.36/fs/pramfs/inode.c
--- linux-2.6.36-orig/fs/pramfs/inode.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.36/fs/pramfs/inode.c	2010-12-15 19:24:14.000000000 +0100
@@ -0,0 +1,729 @@
+/*
+ * BRIEF DESCRIPTION
+ *
+ * Inode methods (allocate/free/read/write).
+ *
+ * Copyright 2009-2010 Marco Stornelli <marco.stornelli@xxxxxxxxx>
+ * Copyright 2003 Sony Corporation
+ * Copyright 2003 Matsushita Electric Industrial Co., Ltd.
+ * 2003-2004 (c) MontaVista Software, Inc. , Steve Longerbeam
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/fs.h>
+#include <linux/smp_lock.h>
+#include <linux/sched.h>
+#include <linux/highuid.h>
+#include <linux/quotaops.h>
+#include <linux/module.h>
+#include <linux/mpage.h>
+#include <linux/backing-dev.h>
+#include "pram.h"
+#include "xattr.h"
+#include "xip.h"
+#include "acl.h"
+
+struct backing_dev_info pram_backing_dev_info __read_mostly = {
+	.ra_pages       = 0,    /* No readahead */
+	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
+};
+
+/*
+ * allocate a data block for inode and return it's absolute blocknr.
+ * Zeroes out the block if zero set. Increments inode->i_blocks.
+ */
+static int pram_new_data_block(struct inode *inode, unsigned long *blocknr, int zero)
+{
+	int errval = pram_new_block(inode->i_sb, blocknr, zero);
+
+	if (!errval) {
+		struct pram_inode *pi = pram_get_inode(inode->i_sb,
+							inode->i_ino);
+		inode->i_blocks++;
+		pram_memunlock_inode(inode->i_sb, pi);
+		pi->i_blocks = cpu_to_be32(inode->i_blocks);
+		pram_memlock_inode(inode->i_sb, pi);
+	}
+
+	return errval;
+}
+
+/*
+ * find the offset to the block represented by the given inode's file
+ * relative block number.
+ */
+u64 pram_find_data_block(struct inode *inode, unsigned long file_blocknr)
+{
+	struct super_block *sb = inode->i_sb;
+	struct pram_inode *pi;
+	u64 *row; /* ptr to row block */
+	u64 *col; /* ptr to column blocks */
+	u64 bp = 0;
+	unsigned int i_row, i_col;
+	unsigned int N = sb->s_blocksize >> 3; /* num block ptrs per block */
+	unsigned int Nbits = sb->s_blocksize_bits - 3;
+
+	pi = pram_get_inode(sb, inode->i_ino);
+
+	i_row = file_blocknr >> Nbits;
+	i_col  = file_blocknr & (N-1);
+
+	row = pram_get_block(sb, be64_to_cpu(pi->i_type.reg.row_block));
+	if (row) {
+		col = pram_get_block(sb, be64_to_cpu(row[i_row]));
+		if (col)
+			bp = be64_to_cpu(col[i_col]);
+	}
+
+	return bp;
+}
+
+/*
+ * Free data blocks from inode in the range start <=> end
+ */
+static void __pram_truncate_blocks(struct inode *inode, loff_t start, loff_t end)
+{
+	struct super_block *sb = inode->i_sb;
+	struct pram_inode *pi = pram_get_inode(sb, inode->i_ino);
+	int N = sb->s_blocksize >> 3; /* num block ptrs per block */
+	int Nbits = sb->s_blocksize_bits - 3;
+	int first_row_index, last_row_index, i, j;
+	unsigned long blocknr, first_blocknr, last_blocknr;
+	unsigned int freed = 0;
+	u64 *row; /* ptr to row block */
+	u64 *col; /* ptr to column blocks */
+
+	if (start > end || !inode->i_blocks || !pi->i_type.reg.row_block)
+		return;
+
+	mutex_lock(&PRAM_I(inode)->truncate_mutex);
+
+	first_blocknr = (start + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
+	last_blocknr = (end + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
+	first_row_index = first_blocknr >> Nbits;
+	last_row_index  = last_blocknr >> Nbits;
+
+	row = pram_get_block(sb, be64_to_cpu(pi->i_type.reg.row_block));
+
+	for (i = first_row_index; i <= last_row_index; i++) {
+		int first_col_index = (i == first_row_index) ?
+			first_blocknr & (N-1) : 0;
+		int last_col_index = (i == last_row_index) ?
+			last_blocknr & (N-1) : N-1;
+
+		if (unlikely(!row[i]))
+			continue;
+
+		col = pram_get_block(sb, be64_to_cpu(row[i]));
+
+		for (j = first_col_index; j <= last_col_index; j++) {
+
+			if (unlikely(!col[j]))
+				continue;
+
+			blocknr = pram_get_blocknr(sb, be64_to_cpu(col[j]));
+			pram_free_block(sb, blocknr);
+			freed++;
+			pram_memunlock_block(sb, col);
+			col[j] = 0;
+			pram_memlock_block(sb, col);
+		}
+
+		if (first_col_index == 0) {
+			blocknr = pram_get_blocknr(sb, be64_to_cpu(row[i]));
+			pram_free_block(sb, blocknr);
+			pram_memunlock_block(sb, row);
+			row[i] = 0;
+			pram_memlock_block(sb, row);
+		}
+	}
+
+	inode->i_blocks -= freed;
+
+	if (start == 0) {
+		blocknr = pram_get_blocknr(sb, be64_to_cpu(pi->i_type.reg.row_block));
+		pram_free_block(sb, blocknr);
+		pram_memunlock_inode(sb, pi);
+		pi->i_type.reg.row_block = 0;
+		pram_memlock_inode(sb, pi);
+	}
+	pram_memunlock_inode(sb, pi);
+	pi->i_blocks = cpu_to_be32(inode->i_blocks);
+	pram_memlock_inode(sb, pi);
+
+	mutex_unlock(&PRAM_I(inode)->truncate_mutex);
+}
+
+static void pram_truncate_blocks(struct inode *inode, loff_t start, loff_t end)
+{
+	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+	      S_ISLNK(inode->i_mode)))
+		return;
+	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
+		return;
+
+	__pram_truncate_blocks(inode, start, end);
+	inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
+	pram_update_inode(inode);
+}
+
+/*
+ * Allocate num data blocks for inode, starting at given file-relative
+ * block number. All blocks except the last are zeroed out.
+ */
+int pram_alloc_blocks(struct inode *inode, int file_blocknr, int num)
+{
+	struct super_block *sb = inode->i_sb;
+	struct pram_inode *pi = pram_get_inode(sb, inode->i_ino);
+	int N = sb->s_blocksize >> 3; /* num block ptrs per block */
+	int Nbits = sb->s_blocksize_bits - 3;
+	int first_file_blocknr;
+	int last_file_blocknr;
+	int first_row_index, last_row_index;
+	int i, j, errval;
+	unsigned long blocknr;
+	u64 *row;
+	u64 *col;
+
+	if (!pi->i_type.reg.row_block) {
+		/* alloc the 2nd order array block */
+		errval = pram_new_block(sb, &blocknr, 1);
+		if (errval) {
+			pram_dbg("failed to alloc 2nd order array block\n");
+			goto fail;
+		}
+		pram_memunlock_inode(sb, pi);
+		pi->i_type.reg.row_block = cpu_to_be64(pram_get_block_off(sb, blocknr));
+		pram_memlock_inode(sb, pi);
+	}
+
+	row = pram_get_block(sb, be64_to_cpu(pi->i_type.reg.row_block));
+
+	first_file_blocknr = file_blocknr;
+	last_file_blocknr = file_blocknr + num - 1;
+
+	first_row_index = first_file_blocknr >> Nbits;
+	last_row_index  = last_file_blocknr >> Nbits;
+
+	for (i = first_row_index; i <= last_row_index; i++) {
+		int first_col_index, last_col_index;
+
+		/*
+		 * we are starting a new row, so make sure
+		 * there is a block allocated for the row.
+		 */
+		if (!row[i]) {
+			/* allocate the row block */
+			errval = pram_new_block(sb, &blocknr, 1);
+			if (errval) {
+				pram_dbg("failed to alloc row block\n");
+				goto fail;
+			}
+			pram_memunlock_block(sb, row);
+			row[i] = cpu_to_be64(pram_get_block_off(sb, blocknr));
+			pram_memlock_block(sb, row);
+		}
+		col = pram_get_block(sb, be64_to_cpu(row[i]));
+
+		first_col_index = (i == first_row_index) ?
+			first_file_blocknr & (N-1) : 0;
+
+		last_col_index = (i == last_row_index) ?
+			last_file_blocknr & (N-1) : N-1;
+
+		for (j = first_col_index; j <= last_col_index; j++) {
+			int last_block =
+				(i == last_row_index) && (j == last_col_index);
+			if (!col[j]) {
+				errval = pram_new_data_block(inode,
+							      &blocknr,
+							      !last_block);
+				if (errval) {
+					pram_dbg("failed to alloc "
+						  "data block\n");
+					goto fail;
+				}
+				pram_memunlock_block(sb, col);
+				col[j] = cpu_to_be64(pram_get_block_off(sb, blocknr));
+				pram_memlock_block(sb, col);
+			}
+		}
+	}
+
+	errval = 0;
+ fail:
+	return errval;
+}
+
+static int pram_read_inode(struct inode *inode, struct pram_inode *pi)
+{
+	int ret = -EIO;
+
+	mutex_lock(&PRAM_I(inode)->i_meta_mutex);
+
+	if (pram_calc_checksum((u8 *)pi, PRAM_INODE_SIZE)) {
+		pram_err(inode->i_sb, "checksum error in inode %08x\n",
+			  (u32)inode->i_ino);
+		goto bad_inode;
+	}
+
+	inode->i_mode = be16_to_cpu(pi->i_mode);
+	inode->i_uid = be32_to_cpu(pi->i_uid);
+	inode->i_gid = be32_to_cpu(pi->i_gid);
+	inode->i_nlink = be16_to_cpu(pi->i_links_count);
+	inode->i_size = be32_to_cpu(pi->i_size);
+	inode->i_atime.tv_sec = be32_to_cpu(pi->i_atime);
+	inode->i_ctime.tv_sec = be32_to_cpu(pi->i_ctime);
+	inode->i_mtime.tv_sec = be32_to_cpu(pi->i_mtime);
+	inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec =
+		inode->i_ctime.tv_nsec = 0;
+	inode->i_generation = be32_to_cpu(pi->i_generation);
+
+	/* check if the inode is active. */
+	if (inode->i_nlink == 0 && (inode->i_mode == 0 || be32_to_cpu(pi->i_dtime))) {
+		/* this inode is deleted */
+		pram_dbg("read inode: inode %lu not active", inode->i_ino);
+		ret = -EINVAL;
+		goto bad_inode;
+	}
+
+	inode->i_blocks = be32_to_cpu(pi->i_blocks);
+	inode->i_ino = pram_get_inodenr(inode->i_sb, pi);
+	inode->i_mapping->a_ops = &pram_aops;
+	inode->i_mapping->backing_dev_info = &pram_backing_dev_info;
+
+	insert_inode_hash(inode);
+	switch (inode->i_mode & S_IFMT) {
+	case S_IFREG:
+		if (pram_use_xip(inode->i_sb)) {
+			inode->i_mapping->a_ops = &pram_aops_xip;
+			inode->i_fop = &pram_xip_file_operations;
+		} else {
+			inode->i_op = &pram_file_inode_operations;
+			inode->i_fop = &pram_file_operations;
+		}
+		break;
+	case S_IFDIR:
+		inode->i_op = &pram_dir_inode_operations;
+		inode->i_fop = &pram_dir_operations;
+		break;
+	case S_IFLNK:
+		inode->i_op = &pram_symlink_inode_operations;
+		break;
+	default:
+		inode->i_size = 0;
+		init_special_inode(inode, inode->i_mode,
+				   be32_to_cpu(pi->i_type.dev.rdev));
+		break;
+	}
+
+	mutex_unlock(&PRAM_I(inode)->i_meta_mutex);
+	return 0;
+
+ bad_inode:
+	make_bad_inode(inode);
+	mutex_unlock(&PRAM_I(inode)->i_meta_mutex);
+	return ret;
+}
+
+int pram_update_inode(struct inode *inode)
+{
+	struct pram_inode *pi;
+	int retval = 0;
+
+	pi = pram_get_inode(inode->i_sb, inode->i_ino);
+	if (!pi)
+		return -EACCES;
+
+	mutex_lock(&PRAM_I(inode)->i_meta_mutex);
+
+	pram_memunlock_inode(inode->i_sb, pi);
+	pi->i_mode = cpu_to_be16(inode->i_mode);
+	pi->i_uid = cpu_to_be32(inode->i_uid);
+	pi->i_gid = cpu_to_be32(inode->i_gid);
+	pi->i_links_count = cpu_to_be16(inode->i_nlink);
+	pi->i_size = cpu_to_be32(inode->i_size);
+	pi->i_blocks = cpu_to_be32(inode->i_blocks);
+	pi->i_atime = cpu_to_be32(inode->i_atime.tv_sec);
+	pi->i_ctime = cpu_to_be32(inode->i_ctime.tv_sec);
+	pi->i_mtime = cpu_to_be32(inode->i_mtime.tv_sec);
+	pi->i_generation = cpu_to_be32(inode->i_generation);
+
+	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
+		pi->i_type.dev.rdev = cpu_to_be32(inode->i_rdev);
+	
+	pram_memlock_inode(inode->i_sb, pi);
+
+	mutex_unlock(&PRAM_I(inode)->i_meta_mutex);
+	return retval;
+}
+
+/*
+ * NOTE! When we get the inode, we're the only people
+ * that have access to it, and as such there are no
+ * race conditions we have to worry about. The inode
+ * is not on the hash-lists, and it cannot be reached
+ * through the filesystem because the directory entry
+ * has been deleted earlier.
+ */
+static void pram_free_inode(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	struct pram_super_block *ps;
+	struct pram_inode *pi;
+	unsigned long inode_nr;
+
+	pram_xattr_delete_inode(inode);
+
+	lock_super(sb);
+
+	inode_nr = (inode->i_ino - PRAM_ROOT_INO) >> PRAM_INODE_BITS;
+
+	pi = pram_get_inode(sb, inode->i_ino);
+	pram_memunlock_inode(sb, pi);
+	pi->i_dtime = cpu_to_be32(get_seconds());
+	pi->i_type.reg.row_block = 0;
+	pi->i_xattr = 0;
+	pram_memlock_inode(sb, pi);
+
+	/* increment s_free_inodes_count */
+	ps = pram_get_super(sb);
+	pram_memunlock_super(sb, ps);
+	if (inode_nr < be32_to_cpu(ps->s_free_inode_hint))
+		ps->s_free_inode_hint = cpu_to_be32(inode_nr);
+	be32_add_cpu(&ps->s_free_inodes_count, 1);
+	if (be32_to_cpu(ps->s_free_inodes_count) == be32_to_cpu(ps->s_inodes_count) - 1) {
+		/* filesystem is empty */
+		pram_dbg("fs is empty!\n");
+		ps->s_free_inode_hint = cpu_to_be32(1);
+	}
+	pram_memlock_super(sb, ps);
+
+	unlock_super(sb);
+}
+
+struct inode *pram_iget(struct super_block *sb, unsigned long ino)
+{
+	struct inode *inode;
+	struct pram_inode *pi;
+	int err;
+
+	inode = iget_locked(sb, ino);
+	if (unlikely(!inode))
+		return ERR_PTR(-ENOMEM);
+	if (!(inode->i_state & I_NEW))
+		return inode;
+
+	pi = pram_get_inode(sb, ino);
+	if (!pi) {
+		err = -EACCES;
+		goto fail;
+	}
+	err = pram_read_inode(inode, pi);
+	if (unlikely(err))
+		goto fail;
+
+	unlock_new_inode(inode);
+	return inode;
+fail:
+	iget_failed(inode);
+	return ERR_PTR(err);
+}
+
+void pram_evict_inode(struct inode *inode)
+{
+	int want_delete = 0;
+
+	if (!inode->i_nlink && !is_bad_inode(inode))
+		want_delete = 1;
+
+	truncate_inode_pages(&inode->i_data, 0);
+
+	if (want_delete) {
+		/* unlink from chain in the inode's directory */
+		pram_remove_link(inode);
+		if (inode->i_blocks)
+			pram_truncate_blocks(inode, 0, inode->i_size);
+		inode->i_size = 0;
+	}
+
+	invalidate_inode_buffers(inode);
+	end_writeback(inode);
+
+	if (want_delete)
+		pram_free_inode(inode);
+}
+
+
+struct inode *pram_new_inode(struct inode *dir, int mode)
+{
+	struct super_block *sb;
+	struct pram_sb_info *sbi;
+	struct pram_super_block *ps;
+	struct inode *inode;
+	struct pram_inode *pi = NULL;
+	int i, errval;
+	ino_t ino = 0;
+
+	sb = dir->i_sb;
+	sbi = (struct pram_sb_info *)sb->s_fs_info;
+	inode = new_inode(sb);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	lock_super(sb);
+	ps = pram_get_super(sb);
+
+	if (ps->s_free_inodes_count) {
+		/* find the oldest unused pram inode */
+		for (i = be32_to_cpu(ps->s_free_inode_hint); i < be32_to_cpu(ps->s_inodes_count); i++) {
+			ino = PRAM_ROOT_INO + (i << PRAM_INODE_BITS);
+			pi = pram_get_inode(sb, ino);
+			/* check if the inode is active. */
+			if (be16_to_cpu(pi->i_links_count) == 0 &&
+			   (be16_to_cpu(pi->i_mode) == 0 ||
+			   be32_to_cpu(pi->i_dtime))) {
+				/* this inode is deleted */
+				break;
+			}
+		}
+
+		if (i >= be32_to_cpu(ps->s_inodes_count)) {
+			pram_err(sb, "s_free_inodes_count!=0 but none free!?\n");
+			errval = -ENOSPC;
+			goto fail1;
+		}
+
+		pram_dbg("allocating inode %lu\n", ino);
+		pram_memunlock_super(sb, ps);
+		be32_add_cpu(&ps->s_free_inodes_count, -1);
+		if (i < be32_to_cpu(ps->s_inodes_count)-1)
+			ps->s_free_inode_hint = cpu_to_be32(i+1);
+		else
+			ps->s_free_inode_hint = 0;
+		pram_memlock_super(sb, ps);
+	} else {
+		pram_dbg("no space left to create new inode!\n");
+		errval = -ENOSPC;
+		goto fail1;
+	}
+
+	/* chosen inode is in ino */
+
+	inode->i_ino = ino;
+	inode_init_owner(inode, dir, mode);
+	inode->i_blocks = inode->i_size = 0;
+	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+
+	inode->i_generation = atomic_add_return(1, &sbi->next_generation);
+
+	pram_memunlock_inode(sb, pi);
+	pi->i_d.d_next = 0;
+	pi->i_d.d_prev = 0;
+	pram_memlock_inode(sb, pi);
+
+	if (insert_inode_locked(inode) < 0) {
+		errval = -EINVAL;
+		goto fail2;
+	}
+	pram_write_inode(inode, 0);
+
+	errval = pram_init_acl(inode, dir);
+	if (errval)
+		goto fail2;
+
+	errval = pram_init_security(inode, dir);
+	if (errval)
+		goto fail2;
+
+	unlock_super(sb);
+
+	return inode;
+fail2:
+	unlock_super(sb);
+	unlock_new_inode(inode);
+	iput(inode);
+	return ERR_PTR(errval);
+fail1:
+	unlock_super(sb);
+	make_bad_inode(inode);
+	iput(inode);
+	return ERR_PTR(errval);
+}
+
+int pram_write_inode(struct inode *inode, struct writeback_control *wbc)
+{
+	return pram_update_inode(inode);
+}
+
+/*
+ * dirty_inode() is called from __mark_inode_dirty()
+ */
+void pram_dirty_inode(struct inode *inode)
+{
+	pram_update_inode(inode);
+}
+
+/* pram_get_and_update_block()
+ *
+ * Look for a block. If not found it can create a new one if create is
+ * different from zero.
+ *
+ * It returns zero if plain lookup failed or blocks mapped or allocated
+ * (plain lookup failed is not an error, e.g. for holes). Minor than zero
+ * otherwise.
+ */
+int pram_get_and_update_block(struct inode *inode, sector_t iblock,
+				     struct buffer_head *bh, int create)
+{
+	struct super_block *sb = inode->i_sb;
+	unsigned int blocksize = 1 << inode->i_blkbits;
+	int err = 0;
+	u64 block;
+	void *bp;
+
+	mutex_lock(&PRAM_I(inode)->truncate_mutex);
+
+	block = pram_find_data_block(inode, iblock);
+
+	if (!block) {
+		if (!create)
+			goto out;
+
+		err = pram_alloc_blocks(inode, iblock, 1);
+		if (err)
+			goto out;
+		block = pram_find_data_block(inode, iblock);
+		if (!block) {
+			err = -EIO;
+			goto out;
+		}
+		set_buffer_new(bh);
+	}
+
+	bh->b_blocknr = block;
+	set_buffer_mapped(bh);
+
+	/* now update the buffer synchronously */
+	bp = pram_get_block(sb, block);
+	if (buffer_new(bh)) {
+		pram_memunlock_block(sb, bp);
+		memset(bp, 0, blocksize);
+		pram_memlock_block(sb, bp);
+		memset(bh->b_data, 0, blocksize);
+	} else {
+		memcpy(bh->b_data, bp, blocksize);
+	}
+
+	set_buffer_uptodate(bh);
+
+ out:
+	mutex_unlock(&PRAM_I(inode)->truncate_mutex);
+	return err;
+}
+
+/*
+ * Called to zeros out a single block. It's used in the "resize"
+ * to avoid to keep data in case the file grow up again.
+ */
+static int pram_clear_block(struct inode *inode, loff_t newsize)
+{
+	pgoff_t index = newsize >> PAGE_CACHE_SHIFT;
+	unsigned long offset = newsize & (PAGE_CACHE_SIZE - 1);
+	unsigned long blocksize, length;
+	sector_t iblock;
+	u64 blockoff;
+	char *bp;
+	int ret = 0;
+
+	blocksize = 1 << inode->i_blkbits;
+	length = offset & (blocksize - 1);
+
+	/* Block boundary ? */
+	if (!length)
+		goto out;
+
+	length = blocksize - length;
+	iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+
+	mutex_lock(&PRAM_I(inode)->truncate_mutex);
+	blockoff = pram_find_data_block(inode, iblock);
+
+	/* Hole ? */
+	if (!blockoff)
+		goto out_unlock;
+
+	bp = pram_get_block(inode->i_sb, blockoff);
+	if (!bp) {
+		ret = -EACCES;
+		goto out_unlock;
+	}
+	pram_memunlock_block(inode->i_sb, bp);
+	memset(bp + offset, 0, length);
+	pram_memlock_block(inode->i_sb, bp);
+
+out_unlock:
+	mutex_unlock(&PRAM_I(inode)->truncate_mutex);
+out:
+	return ret;
+}
+
+static int pram_setsize(struct inode *inode, loff_t newsize)
+{
+	int ret = 0;
+	loff_t oldsize;
+
+	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+	    S_ISLNK(inode->i_mode)))
+		return -EINVAL;
+	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
+		return -EPERM;
+
+	if (mapping_is_xip(inode->i_mapping))
+		ret = xip_truncate_page(inode->i_mapping, newsize);
+	else
+		ret = pram_clear_block(inode, newsize);
+	if (ret)
+		return ret;
+
+	oldsize = inode->i_size;
+	i_size_write(inode, newsize);
+	__pram_truncate_blocks(inode, newsize, oldsize);
+	inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
+	pram_update_inode(inode);
+
+	return ret;
+}
+
+int pram_notify_change(struct dentry *dentry, struct iattr *attr)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = inode_change_ok(inode, attr);
+	if (error)
+		return error;
+
+	if (attr->ia_valid & ATTR_SIZE && attr->ia_size != inode->i_size) {
+		error = pram_setsize(inode, attr->ia_size);
+		if (error)
+			return error;
+	}
+	setattr_copy(inode, attr);
+	if (attr->ia_valid & ATTR_MODE)
+		error = pram_acl_chmod(inode);
+	error = pram_update_inode(inode);
+
+	return error;
+}
+
+struct address_space_operations pram_aops = {
+	.readpage	= pram_readpage,
+	.direct_IO	= pram_direct_IO,
+};
+
+struct address_space_operations pram_aops_xip = {
+	.get_xip_mem	= pram_get_xip_mem,
+};
--
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