From 98d917047e8b7f4bb2ff61d81b0ccd94a00444f9 Mon Sep 17 00:00:00 2001

From: Namjae Jeon <namjae.jeon@samsung.com>

Date: Mon, 2 Mar 2020 15:21:36 +0900

Subject: [Backport 98d917047e8b] exfat: add file operations

MIME-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

This adds the implementation of file operations for exfat.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>

Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>

Reviewed-by: Pali Rohár <pali.rohar@gmail.com>

Reviewed-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

---

 src/file.c | 360 ++++++++++++++++++++++++++++++++++++++++++++++++

 1 file changed, 360 insertions(+)

 create mode 100644 src/file.c

diff --git a/src/file.c b/src/file.c

new file mode 100644

index 0000000000000000000000000000000000000000..483f683757aa87420ba347afd3c9db9e94b8a14d

--- /dev/null

+++ b/src/file.c

@@ -0,0 +1,360 @@

+// SPDX-License-Identifier: GPL-2.0-or-later

+/*

+ * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.

+ */

+

+#include <linux/slab.h>

+#include <linux/cred.h>

+#include <linux/buffer_head.h>

+

+#include "exfat_raw.h"

+#include "exfat_fs.h"

+

+static int exfat_cont_expand(struct inode *inode, loff_t size)

+{

+	struct address_space *mapping = inode->i_mapping;

+	loff_t start = i_size_read(inode), count = size - i_size_read(inode);

+	int err, err2;

+

+	err = generic_cont_expand_simple(inode, size);

+	if (err)

+		return err;

+

+	inode->i_ctime = inode->i_mtime = current_time(inode);

+	mark_inode_dirty(inode);

+

+	if (!IS_SYNC(inode))

+		return 0;

+

+	err = filemap_fdatawrite_range(mapping, start, start + count - 1);

+	err2 = sync_mapping_buffers(mapping);

+	if (!err)

+		err = err2;

+	err2 = write_inode_now(inode, 1);

+	if (!err)

+		err = err2;

+	if (err)

+		return err;

+

+	return filemap_fdatawait_range(mapping, start, start + count - 1);

+}

+

+static bool exfat_allow_set_time(struct exfat_sb_info *sbi, struct inode *inode)

+{

+	mode_t allow_utime = sbi->options.allow_utime;

+

+	if (!uid_eq(current_fsuid(), inode->i_uid)) {

+		if (in_group_p(inode->i_gid))

+			allow_utime >>= 3;

+		if (allow_utime & MAY_WRITE)

+			return true;

+	}

+

+	/* use a default check */

+	return false;

+}

+

+static int exfat_sanitize_mode(const struct exfat_sb_info *sbi,

+		struct inode *inode, umode_t *mode_ptr)

+{

+	mode_t i_mode, mask, perm;

+

+	i_mode = inode->i_mode;

+

+	mask = (S_ISREG(i_mode) || S_ISLNK(i_mode)) ?

+		sbi->options.fs_fmask : sbi->options.fs_dmask;

+	perm = *mode_ptr & ~(S_IFMT | mask);

+

+	/* Of the r and x bits, all (subject to umask) must be present.*/

+	if ((perm & 0555) != (i_mode & 0555))

+		return -EPERM;

+

+	if (exfat_mode_can_hold_ro(inode)) {

+		/*

+		 * Of the w bits, either all (subject to umask) or none must

+		 * be present.

+		 */

+		if ((perm & 0222) && ((perm & 0222) != (0222 & ~mask)))

+			return -EPERM;

+	} else {

+		/*

+		 * If exfat_mode_can_hold_ro(inode) is false, can't change

+		 * w bits.

+		 */

+		if ((perm & 0222) != (0222 & ~mask))

+			return -EPERM;

+	}

+

+	*mode_ptr &= S_IFMT | perm;

+

+	return 0;

+}

+

+/* resize the file length */

+int __exfat_truncate(struct inode *inode, loff_t new_size)

+{

+	unsigned int num_clusters_new, num_clusters_phys;

+	unsigned int last_clu = EXFAT_FREE_CLUSTER;

+	struct exfat_chain clu;

+	struct exfat_dentry *ep, *ep2;

+	struct super_block *sb = inode->i_sb;

+	struct exfat_sb_info *sbi = EXFAT_SB(sb);

+	struct exfat_inode_info *ei = EXFAT_I(inode);

+	struct exfat_entry_set_cache *es = NULL;

+	int evict = (ei->dir.dir == DIR_DELETED) ? 1 : 0;

+

+	/* check if the given file ID is opened */

+	if (ei->type != TYPE_FILE && ei->type != TYPE_DIR)

+		return -EPERM;

+

+	exfat_set_vol_flags(sb, VOL_DIRTY);

+

+	num_clusters_new = EXFAT_B_TO_CLU_ROUND_UP(i_size_read(inode), sbi);

+	num_clusters_phys =

+		EXFAT_B_TO_CLU_ROUND_UP(EXFAT_I(inode)->i_size_ondisk, sbi);

+

+	exfat_chain_set(&clu, ei->start_clu, num_clusters_phys, ei->flags);

+

+	if (new_size > 0) {

+		/*

+		 * Truncate FAT chain num_clusters after the first cluster

+		 * num_clusters = min(new, phys);

+		 */

+		unsigned int num_clusters =

+			min(num_clusters_new, num_clusters_phys);

+

+		/*

+		 * Follow FAT chain

+		 * (defensive coding - works fine even with corrupted FAT table

+		 */

+		if (clu.flags == ALLOC_NO_FAT_CHAIN) {

+			clu.dir += num_clusters;

+			clu.size -= num_clusters;

+		} else {

+			while (num_clusters > 0) {

+				last_clu = clu.dir;

+				if (exfat_get_next_cluster(sb, &(clu.dir)))

+					return -EIO;

+

+				num_clusters--;

+				clu.size--;

+			}

+		}

+	} else {

+		ei->flags = ALLOC_NO_FAT_CHAIN;

+		ei->start_clu = EXFAT_EOF_CLUSTER;

+	}

+

+	i_size_write(inode, new_size);

+

+	if (ei->type == TYPE_FILE)

+		ei->attr |= ATTR_ARCHIVE;

+

+	/* update the directory entry */

+	if (!evict) {

+		struct timespec64 ts;

+

+		es = exfat_get_dentry_set(sb, &(ei->dir), ei->entry,

+				ES_ALL_ENTRIES, &ep);

+		if (!es)

+			return -EIO;

+		ep2 = ep + 1;

+

+		ts = current_time(inode);

+		exfat_set_entry_time(sbi, &ts,

+				&ep->dentry.file.modify_tz,

+				&ep->dentry.file.modify_time,

+				&ep->dentry.file.modify_date,

+				&ep->dentry.file.modify_time_ms);

+		ep->dentry.file.attr = cpu_to_le16(ei->attr);

+

+		/* File size should be zero if there is no cluster allocated */

+		if (ei->start_clu == EXFAT_EOF_CLUSTER) {

+			ep->dentry.stream.valid_size = 0;

+			ep->dentry.stream.size = 0;

+		} else {

+			ep->dentry.stream.valid_size = cpu_to_le64(new_size);

+			ep->dentry.stream.size = ep->dentry.stream.valid_size;

+		}

+

+		if (new_size == 0) {

+			/* Any directory can not be truncated to zero */

+			WARN_ON(ei->type != TYPE_FILE);

+

+			ep2->dentry.stream.flags = ALLOC_FAT_CHAIN;

+			ep2->dentry.stream.start_clu = EXFAT_FREE_CLUSTER;

+		}

+

+		if (exfat_update_dir_chksum_with_entry_set(sb, es,

+		    inode_needs_sync(inode)))

+			return -EIO;

+		kfree(es);

+	}

+

+	/* cut off from the FAT chain */

+	if (ei->flags == ALLOC_FAT_CHAIN && last_clu != EXFAT_FREE_CLUSTER &&

+			last_clu != EXFAT_EOF_CLUSTER) {

+		if (exfat_ent_set(sb, last_clu, EXFAT_EOF_CLUSTER))

+			return -EIO;

+	}

+

+	/* invalidate cache and free the clusters */

+	/* clear exfat cache */

+	exfat_cache_inval_inode(inode);

+

+	/* hint information */

+	ei->hint_bmap.off = EXFAT_EOF_CLUSTER;

+	ei->hint_bmap.clu = EXFAT_EOF_CLUSTER;

+	if (ei->rwoffset > new_size)

+		ei->rwoffset = new_size;

+

+	/* hint_stat will be used if this is directory. */

+	ei->hint_stat.eidx = 0;

+	ei->hint_stat.clu = ei->start_clu;

+	ei->hint_femp.eidx = EXFAT_HINT_NONE;

+

+	/* free the clusters */

+	if (exfat_free_cluster(inode, &clu))

+		return -EIO;

+

+	exfat_set_vol_flags(sb, VOL_CLEAN);

+

+	return 0;

+}

+

+void exfat_truncate(struct inode *inode, loff_t size)

+{

+	struct super_block *sb = inode->i_sb;

+	struct exfat_sb_info *sbi = EXFAT_SB(sb);

+	unsigned int blocksize = 1 << inode->i_blkbits;

+	loff_t aligned_size;

+	int err;

+

+	mutex_lock(&sbi->s_lock);

+	if (EXFAT_I(inode)->start_clu == 0) {

+		/*

+		 * Empty start_clu != ~0 (not allocated)

+		 */

+		exfat_fs_error(sb, "tried to truncate zeroed cluster.");

+		goto write_size;

+	}

+

+	err = __exfat_truncate(inode, i_size_read(inode));

+	if (err)

+		goto write_size;

+

+	inode->i_ctime = inode->i_mtime = current_time(inode);

+	if (IS_DIRSYNC(inode))

+		exfat_sync_inode(inode);

+	else

+		mark_inode_dirty(inode);

+

+	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &

+			~(sbi->cluster_size - 1)) >> inode->i_blkbits;

+write_size:

+	aligned_size = i_size_read(inode);

+	if (aligned_size & (blocksize - 1)) {

+		aligned_size |= (blocksize - 1);

+		aligned_size++;

+	}

+

+	if (EXFAT_I(inode)->i_size_ondisk > i_size_read(inode))

+		EXFAT_I(inode)->i_size_ondisk = aligned_size;

+

+	if (EXFAT_I(inode)->i_size_aligned > i_size_read(inode))

+		EXFAT_I(inode)->i_size_aligned = aligned_size;

+	mutex_unlock(&sbi->s_lock);

+}

+

+int exfat_getattr(const struct path *path, struct kstat *stat,

+		unsigned int request_mask, unsigned int query_flags)

+{

+	struct inode *inode = d_backing_inode(path->dentry);

+	struct exfat_inode_info *ei = EXFAT_I(inode);

+

+	generic_fillattr(inode, stat);

+	stat->result_mask |= STATX_BTIME;

+	stat->btime.tv_sec = ei->i_crtime.tv_sec;

+	stat->btime.tv_nsec = ei->i_crtime.tv_nsec;

+	stat->blksize = EXFAT_SB(inode->i_sb)->cluster_size;

+	return 0;

+}

+

+int exfat_setattr(struct dentry *dentry, struct iattr *attr)

+{

+	struct exfat_sb_info *sbi = EXFAT_SB(dentry->d_sb);

+	struct inode *inode = dentry->d_inode;

+	unsigned int ia_valid;

+	int error;

+

+	if ((attr->ia_valid & ATTR_SIZE) &&

+	    attr->ia_size > i_size_read(inode)) {

+		error = exfat_cont_expand(inode, attr->ia_size);

+		if (error || attr->ia_valid == ATTR_SIZE)

+			return error;

+		attr->ia_valid &= ~ATTR_SIZE;

+	}

+

+	/* Check for setting the inode time. */

+	ia_valid = attr->ia_valid;

+	if ((ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) &&

+	    exfat_allow_set_time(sbi, inode)) {

+		attr->ia_valid &= ~(ATTR_MTIME_SET | ATTR_ATIME_SET |

+				ATTR_TIMES_SET);

+	}

+

+	error = setattr_prepare(dentry, attr);

+	attr->ia_valid = ia_valid;

+	if (error)

+		goto out;

+

+	if (((attr->ia_valid & ATTR_UID) &&

+	     !uid_eq(attr->ia_uid, sbi->options.fs_uid)) ||

+	    ((attr->ia_valid & ATTR_GID) &&

+	     !gid_eq(attr->ia_gid, sbi->options.fs_gid)) ||

+	    ((attr->ia_valid & ATTR_MODE) &&

+	     (attr->ia_mode & ~(S_IFREG | S_IFLNK | S_IFDIR | 0777)))) {

+		error = -EPERM;

+		goto out;

+	}

+

+	/*

+	 * We don't return -EPERM here. Yes, strange, but this is too

+	 * old behavior.

+	 */

+	if (attr->ia_valid & ATTR_MODE) {

+		if (exfat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)

+			attr->ia_valid &= ~ATTR_MODE;

+	}

+

+	if (attr->ia_valid & ATTR_SIZE) {

+		error = exfat_block_truncate_page(inode, attr->ia_size);

+		if (error)

+			goto out;

+

+		down_write(&EXFAT_I(inode)->truncate_lock);

+		truncate_setsize(inode, attr->ia_size);

+		exfat_truncate(inode, attr->ia_size);

+		up_write(&EXFAT_I(inode)->truncate_lock);

+	}

+

+	setattr_copy(inode, attr);

+	mark_inode_dirty(inode);

+

+out:

+	return error;

+}

+

+const struct file_operations exfat_file_operations = {

+	.llseek      = generic_file_llseek,

+	.read_iter   = generic_file_read_iter,

+	.write_iter  = generic_file_write_iter,

+	.mmap        = generic_file_mmap,

+	.fsync       = generic_file_fsync,

+	.splice_read = generic_file_splice_read,

+};

+

+const struct inode_operations exfat_file_inode_operations = {

+	.setattr     = exfat_setattr,

+	.getattr     = exfat_getattr,

+};

-- 

2.31.1