eCryptfs: delay writing 0's after llseek until write (53a2731f) · Commits · 戴 / test

fs/ecryptfs/file.c

+1 −58

Original line number	Diff line number	Diff line
		@@ -32,63 +32,6 @@
		#include <linux/fs_stack.h>
		#include "ecryptfs_kernel.h"

		/**
		* ecryptfs_llseek
		* @file: File we are seeking in
		* @offset: The offset to seek to
		* @origin: 2 - offset from i_size; 1 - offset from f_pos
		*
		* Returns the position we have seeked to, or negative on error
		*/
		static loff_t ecryptfs_llseek(struct file *file, loff_t offset, int origin)
		{
		loff_t rv;
		loff_t new_end_pos;
		int rc;
		int expanding_file = 0;
		struct inode *inode = file->f_mapping->host;

		/* If our offset is past the end of our file, we're going to
		* need to grow it so we have a valid length of 0's */
		new_end_pos = offset;
		switch (origin) {
		case 2:
		new_end_pos += i_size_read(inode);
		expanding_file = 1;
		break;
		case 1:
		new_end_pos += file->f_pos;
		if (new_end_pos > i_size_read(inode)) {
		ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
		"> i_size_read(inode)(=[0x%.16x])\n",
		new_end_pos, i_size_read(inode));
		expanding_file = 1;
		}
		break;
		default:
		if (new_end_pos > i_size_read(inode)) {
		ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
		"> i_size_read(inode)(=[0x%.16x])\n",
		new_end_pos, i_size_read(inode));
		expanding_file = 1;
		}
		}
		ecryptfs_printk(KERN_DEBUG, "new_end_pos = [0x%.16x]\n", new_end_pos);
		if (expanding_file) {
		rc = ecryptfs_truncate(file->f_path.dentry, new_end_pos);
		if (rc) {
		rv = rc;
		ecryptfs_printk(KERN_ERR, "Error on attempt to "
		"truncate to (higher) offset [0x%.16x];"
		" rc = [%d]\n", new_end_pos, rc);
		goto out;
		}
		}
		rv = generic_file_llseek(file, offset, origin);
		out:
		return rv;
		}

		/**
		* ecryptfs_read_update_atime
		*
		@@ -425,7 +368,7 @@ const struct file_operations ecryptfs_dir_fops = {
		};

		const struct file_operations ecryptfs_main_fops = {
		.llseek = ecryptfs_llseek,
		.llseek = generic_file_llseek,
		.read = do_sync_read,
		.aio_read = ecryptfs_read_update_atime,
		.write = do_sync_write,

fs/ecryptfs/mmap.c

+35 −3

Original line number	Diff line number	Diff line
		@@ -376,9 +376,31 @@ out:
		return 0;
		}

		/**
		* eCryptfs does not currently support holes. When writing after a
		* seek past the end of the file, eCryptfs fills in 0's through to the
		* current location. The code to fill in the 0's to all the
		* intermediate pages calls ecryptfs_prepare_write_no_truncate().
		*/
		static int
		ecryptfs_prepare_write_no_truncate(struct file file, struct page page,
		unsigned from, unsigned to)
		{
		int rc = 0;

		if (from == 0 && to == PAGE_CACHE_SIZE)
		goto out; /* If we are writing a full page, it will be
		up to date. */
		if (!PageUptodate(page))
		rc = ecryptfs_do_readpage(file, page, page->index);
		out:
		return rc;
		}

		static int ecryptfs_prepare_write(struct file file, struct page page,
		unsigned from, unsigned to)
		{
		loff_t pos;
		int rc = 0;

		if (from == 0 && to == PAGE_CACHE_SIZE)
		@@ -386,6 +408,16 @@ static int ecryptfs_prepare_write(struct file file, struct page page,
		up to date. */
		if (!PageUptodate(page))
		rc = ecryptfs_do_readpage(file, page, page->index);
		pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
		if (pos > i_size_read(page->mapping->host)) {
		rc = ecryptfs_truncate(file->f_path.dentry, pos);
		if (rc) {
		printk(KERN_ERR "Error on attempt to "
		"truncate to (higher) offset [%lld];"
		" rc = [%d]\n", pos, rc);
		goto out;
		}
		}
		out:
		return rc;
		}
		@@ -744,10 +776,10 @@ int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
		rc = PTR_ERR(tmp_page);
		goto out;
		}
		rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros);
		if (rc) {
		if ((rc = ecryptfs_prepare_write_no_truncate(file, tmp_page, start,
		(start + num_zeros)))) {
		ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
		"to remainder of page at index [0x%.16x]\n",
		"to page at index [0x%.16x]\n",
		index);
		page_cache_release(tmp_page);
		goto out;

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