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678 lines
18 KiB
678 lines
18 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* linux/fs/ext4/dir.c |
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* |
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* Copyright (C) 1992, 1993, 1994, 1995 |
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* Remy Card ([email protected]) |
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* Laboratoire MASI - Institut Blaise Pascal |
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* Universite Pierre et Marie Curie (Paris VI) |
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* |
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* from |
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* |
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* linux/fs/minix/dir.c |
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* |
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* Copyright (C) 1991, 1992 Linus Torvalds |
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* |
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* ext4 directory handling functions |
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* |
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* Big-endian to little-endian byte-swapping/bitmaps by |
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* David S. Miller ([email protected]), 1995 |
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* |
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* Hash Tree Directory indexing (c) 2001 Daniel Phillips |
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* |
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*/ |
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|
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#include <linux/fs.h> |
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#include <linux/buffer_head.h> |
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#include <linux/slab.h> |
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#include <linux/iversion.h> |
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#include <linux/unicode.h> |
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#include "ext4.h" |
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#include "xattr.h" |
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|
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static int ext4_dx_readdir(struct file *, struct dir_context *); |
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|
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/** |
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* is_dx_dir() - check if a directory is using htree indexing |
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* @inode: directory inode |
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* |
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* Check if the given dir-inode refers to an htree-indexed directory |
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* (or a directory which could potentially get converted to use htree |
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* indexing). |
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* |
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* Return 1 if it is a dx dir, 0 if not |
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*/ |
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static int is_dx_dir(struct inode *inode) |
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{ |
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struct super_block *sb = inode->i_sb; |
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|
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if (ext4_has_feature_dir_index(inode->i_sb) && |
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((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) || |
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((inode->i_size >> sb->s_blocksize_bits) == 1) || |
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ext4_has_inline_data(inode))) |
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return 1; |
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|
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return 0; |
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} |
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|
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static bool is_fake_dir_entry(struct ext4_dir_entry_2 *de) |
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{ |
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/* Check if . or .. , or skip if namelen is 0 */ |
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if ((de->name_len > 0) && (de->name_len <= 2) && (de->name[0] == '.') && |
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(de->name[1] == '.' || de->name[1] == '\0')) |
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return true; |
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/* Check if this is a csum entry */ |
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if (de->file_type == EXT4_FT_DIR_CSUM) |
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return true; |
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return false; |
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} |
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|
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/* |
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* Return 0 if the directory entry is OK, and 1 if there is a problem |
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* |
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* Note: this is the opposite of what ext2 and ext3 historically returned... |
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* |
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* bh passed here can be an inode block or a dir data block, depending |
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* on the inode inline data flag. |
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*/ |
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int __ext4_check_dir_entry(const char *function, unsigned int line, |
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struct inode *dir, struct file *filp, |
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struct ext4_dir_entry_2 *de, |
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struct buffer_head *bh, char *buf, int size, |
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unsigned int offset) |
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{ |
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const char *error_msg = NULL; |
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const int rlen = ext4_rec_len_from_disk(de->rec_len, |
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dir->i_sb->s_blocksize); |
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const int next_offset = ((char *) de - buf) + rlen; |
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bool fake = is_fake_dir_entry(de); |
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bool has_csum = ext4_has_metadata_csum(dir->i_sb); |
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if (unlikely(rlen < ext4_dir_rec_len(1, fake ? NULL : dir))) |
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error_msg = "rec_len is smaller than minimal"; |
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else if (unlikely(rlen % 4 != 0)) |
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error_msg = "rec_len % 4 != 0"; |
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else if (unlikely(rlen < ext4_dir_rec_len(de->name_len, |
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fake ? NULL : dir))) |
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error_msg = "rec_len is too small for name_len"; |
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else if (unlikely(next_offset > size)) |
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error_msg = "directory entry overrun"; |
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else if (unlikely(next_offset > size - ext4_dir_rec_len(1, |
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has_csum ? NULL : dir) && |
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next_offset != size)) |
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error_msg = "directory entry too close to block end"; |
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else if (unlikely(le32_to_cpu(de->inode) > |
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le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) |
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error_msg = "inode out of bounds"; |
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else |
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return 0; |
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|
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if (filp) |
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ext4_error_file(filp, function, line, bh->b_blocknr, |
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"bad entry in directory: %s - offset=%u, " |
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"inode=%u, rec_len=%d, size=%d fake=%d", |
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error_msg, offset, le32_to_cpu(de->inode), |
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rlen, size, fake); |
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else |
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ext4_error_inode(dir, function, line, bh->b_blocknr, |
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"bad entry in directory: %s - offset=%u, " |
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"inode=%u, rec_len=%d, size=%d fake=%d", |
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error_msg, offset, le32_to_cpu(de->inode), |
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rlen, size, fake); |
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|
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return 1; |
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} |
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static int ext4_readdir(struct file *file, struct dir_context *ctx) |
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{ |
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unsigned int offset; |
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int i; |
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struct ext4_dir_entry_2 *de; |
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int err; |
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struct inode *inode = file_inode(file); |
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struct super_block *sb = inode->i_sb; |
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struct buffer_head *bh = NULL; |
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struct fscrypt_str fstr = FSTR_INIT(NULL, 0); |
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|
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err = fscrypt_prepare_readdir(inode); |
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if (err) |
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return err; |
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|
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if (is_dx_dir(inode)) { |
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err = ext4_dx_readdir(file, ctx); |
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if (err != ERR_BAD_DX_DIR) |
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return err; |
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|
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/* Can we just clear INDEX flag to ignore htree information? */ |
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if (!ext4_has_metadata_csum(sb)) { |
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/* |
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* We don't set the inode dirty flag since it's not |
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* critical that it gets flushed back to the disk. |
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*/ |
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ext4_clear_inode_flag(inode, EXT4_INODE_INDEX); |
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} |
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} |
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|
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if (ext4_has_inline_data(inode)) { |
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int has_inline_data = 1; |
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err = ext4_read_inline_dir(file, ctx, |
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&has_inline_data); |
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if (has_inline_data) |
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return err; |
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} |
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if (IS_ENCRYPTED(inode)) { |
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err = fscrypt_fname_alloc_buffer(EXT4_NAME_LEN, &fstr); |
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if (err < 0) |
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return err; |
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} |
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|
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while (ctx->pos < inode->i_size) { |
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struct ext4_map_blocks map; |
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|
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if (fatal_signal_pending(current)) { |
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err = -ERESTARTSYS; |
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goto errout; |
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} |
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cond_resched(); |
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offset = ctx->pos & (sb->s_blocksize - 1); |
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map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb); |
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map.m_len = 1; |
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err = ext4_map_blocks(NULL, inode, &map, 0); |
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if (err == 0) { |
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/* m_len should never be zero but let's avoid |
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* an infinite loop if it somehow is */ |
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if (map.m_len == 0) |
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map.m_len = 1; |
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ctx->pos += map.m_len * sb->s_blocksize; |
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continue; |
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} |
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if (err > 0) { |
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pgoff_t index = map.m_pblk >> |
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(PAGE_SHIFT - inode->i_blkbits); |
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if (!ra_has_index(&file->f_ra, index)) |
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page_cache_sync_readahead( |
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sb->s_bdev->bd_inode->i_mapping, |
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&file->f_ra, file, |
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index, 1); |
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file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT; |
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bh = ext4_bread(NULL, inode, map.m_lblk, 0); |
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if (IS_ERR(bh)) { |
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err = PTR_ERR(bh); |
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bh = NULL; |
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goto errout; |
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} |
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} |
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if (!bh) { |
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/* corrupt size? Maybe no more blocks to read */ |
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if (ctx->pos > inode->i_blocks << 9) |
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break; |
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ctx->pos += sb->s_blocksize - offset; |
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continue; |
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} |
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/* Check the checksum */ |
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if (!buffer_verified(bh) && |
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!ext4_dirblock_csum_verify(inode, bh)) { |
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EXT4_ERROR_FILE(file, 0, "directory fails checksum " |
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"at offset %llu", |
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(unsigned long long)ctx->pos); |
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ctx->pos += sb->s_blocksize - offset; |
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brelse(bh); |
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bh = NULL; |
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continue; |
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} |
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set_buffer_verified(bh); |
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|
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/* If the dir block has changed since the last call to |
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* readdir(2), then we might be pointing to an invalid |
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* dirent right now. Scan from the start of the block |
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* to make sure. */ |
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if (!inode_eq_iversion(inode, file->f_version)) { |
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for (i = 0; i < sb->s_blocksize && i < offset; ) { |
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de = (struct ext4_dir_entry_2 *) |
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(bh->b_data + i); |
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/* It's too expensive to do a full |
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* dirent test each time round this |
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* loop, but we do have to test at |
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* least that it is non-zero. A |
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* failure will be detected in the |
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* dirent test below. */ |
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if (ext4_rec_len_from_disk(de->rec_len, |
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sb->s_blocksize) < ext4_dir_rec_len(1, |
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inode)) |
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break; |
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i += ext4_rec_len_from_disk(de->rec_len, |
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sb->s_blocksize); |
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} |
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offset = i; |
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ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) |
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| offset; |
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file->f_version = inode_query_iversion(inode); |
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} |
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while (ctx->pos < inode->i_size |
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&& offset < sb->s_blocksize) { |
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de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); |
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if (ext4_check_dir_entry(inode, file, de, bh, |
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bh->b_data, bh->b_size, |
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offset)) { |
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/* |
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* On error, skip to the next block |
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*/ |
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ctx->pos = (ctx->pos | |
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(sb->s_blocksize - 1)) + 1; |
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break; |
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} |
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offset += ext4_rec_len_from_disk(de->rec_len, |
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sb->s_blocksize); |
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if (le32_to_cpu(de->inode)) { |
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if (!IS_ENCRYPTED(inode)) { |
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if (!dir_emit(ctx, de->name, |
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de->name_len, |
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le32_to_cpu(de->inode), |
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get_dtype(sb, de->file_type))) |
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goto done; |
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} else { |
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int save_len = fstr.len; |
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struct fscrypt_str de_name = |
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FSTR_INIT(de->name, |
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de->name_len); |
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/* Directory is encrypted */ |
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err = fscrypt_fname_disk_to_usr(inode, |
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EXT4_DIRENT_HASH(de), |
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EXT4_DIRENT_MINOR_HASH(de), |
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&de_name, &fstr); |
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de_name = fstr; |
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fstr.len = save_len; |
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if (err) |
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goto errout; |
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if (!dir_emit(ctx, |
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de_name.name, de_name.len, |
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le32_to_cpu(de->inode), |
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get_dtype(sb, de->file_type))) |
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goto done; |
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} |
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} |
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ctx->pos += ext4_rec_len_from_disk(de->rec_len, |
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sb->s_blocksize); |
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} |
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if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode)) |
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goto done; |
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brelse(bh); |
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bh = NULL; |
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offset = 0; |
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} |
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done: |
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err = 0; |
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errout: |
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fscrypt_fname_free_buffer(&fstr); |
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brelse(bh); |
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return err; |
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} |
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static inline int is_32bit_api(void) |
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{ |
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#ifdef CONFIG_COMPAT |
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return in_compat_syscall(); |
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#else |
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return (BITS_PER_LONG == 32); |
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#endif |
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} |
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/* |
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* These functions convert from the major/minor hash to an f_pos |
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* value for dx directories |
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* |
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* Upper layer (for example NFS) should specify FMODE_32BITHASH or |
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* FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted |
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* directly on both 32-bit and 64-bit nodes, under such case, neither |
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* FMODE_32BITHASH nor FMODE_64BITHASH is specified. |
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*/ |
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static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) |
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{ |
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if ((filp->f_mode & FMODE_32BITHASH) || |
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) |
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return major >> 1; |
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else |
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return ((__u64)(major >> 1) << 32) | (__u64)minor; |
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} |
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static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) |
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{ |
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if ((filp->f_mode & FMODE_32BITHASH) || |
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) |
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return (pos << 1) & 0xffffffff; |
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else |
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return ((pos >> 32) << 1) & 0xffffffff; |
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} |
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static inline __u32 pos2min_hash(struct file *filp, loff_t pos) |
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{ |
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if ((filp->f_mode & FMODE_32BITHASH) || |
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) |
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return 0; |
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else |
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return pos & 0xffffffff; |
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} |
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/* |
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* Return 32- or 64-bit end-of-file for dx directories |
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*/ |
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static inline loff_t ext4_get_htree_eof(struct file *filp) |
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{ |
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if ((filp->f_mode & FMODE_32BITHASH) || |
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(!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) |
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return EXT4_HTREE_EOF_32BIT; |
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else |
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return EXT4_HTREE_EOF_64BIT; |
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} |
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/* |
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* ext4_dir_llseek() calls generic_file_llseek_size to handle htree |
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* directories, where the "offset" is in terms of the filename hash |
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* value instead of the byte offset. |
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* |
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* Because we may return a 64-bit hash that is well beyond offset limits, |
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* we need to pass the max hash as the maximum allowable offset in |
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* the htree directory case. |
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* |
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* For non-htree, ext4_llseek already chooses the proper max offset. |
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*/ |
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static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) |
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{ |
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struct inode *inode = file->f_mapping->host; |
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int dx_dir = is_dx_dir(inode); |
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loff_t ret, htree_max = ext4_get_htree_eof(file); |
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if (likely(dx_dir)) |
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ret = generic_file_llseek_size(file, offset, whence, |
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htree_max, htree_max); |
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else |
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ret = ext4_llseek(file, offset, whence); |
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file->f_version = inode_peek_iversion(inode) - 1; |
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return ret; |
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} |
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/* |
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* This structure holds the nodes of the red-black tree used to store |
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* the directory entry in hash order. |
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*/ |
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struct fname { |
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__u32 hash; |
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__u32 minor_hash; |
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struct rb_node rb_hash; |
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struct fname *next; |
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__u32 inode; |
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__u8 name_len; |
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__u8 file_type; |
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char name[]; |
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}; |
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/* |
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* This functoin implements a non-recursive way of freeing all of the |
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* nodes in the red-black tree. |
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*/ |
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static void free_rb_tree_fname(struct rb_root *root) |
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{ |
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struct fname *fname, *next; |
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rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash) |
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while (fname) { |
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struct fname *old = fname; |
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fname = fname->next; |
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kfree(old); |
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} |
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*root = RB_ROOT; |
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} |
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static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, |
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loff_t pos) |
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{ |
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struct dir_private_info *p; |
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p = kzalloc(sizeof(*p), GFP_KERNEL); |
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if (!p) |
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return NULL; |
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p->curr_hash = pos2maj_hash(filp, pos); |
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p->curr_minor_hash = pos2min_hash(filp, pos); |
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return p; |
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} |
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void ext4_htree_free_dir_info(struct dir_private_info *p) |
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{ |
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free_rb_tree_fname(&p->root); |
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kfree(p); |
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} |
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|
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/* |
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* Given a directory entry, enter it into the fname rb tree. |
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* |
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* When filename encryption is enabled, the dirent will hold the |
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* encrypted filename, while the htree will hold decrypted filename. |
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* The decrypted filename is passed in via ent_name. parameter. |
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*/ |
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int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, |
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__u32 minor_hash, |
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struct ext4_dir_entry_2 *dirent, |
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struct fscrypt_str *ent_name) |
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{ |
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struct rb_node **p, *parent = NULL; |
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struct fname *fname, *new_fn; |
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struct dir_private_info *info; |
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int len; |
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|
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info = dir_file->private_data; |
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p = &info->root.rb_node; |
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|
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/* Create and allocate the fname structure */ |
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len = sizeof(struct fname) + ent_name->len + 1; |
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new_fn = kzalloc(len, GFP_KERNEL); |
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if (!new_fn) |
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return -ENOMEM; |
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new_fn->hash = hash; |
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new_fn->minor_hash = minor_hash; |
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new_fn->inode = le32_to_cpu(dirent->inode); |
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new_fn->name_len = ent_name->len; |
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new_fn->file_type = dirent->file_type; |
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memcpy(new_fn->name, ent_name->name, ent_name->len); |
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|
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while (*p) { |
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parent = *p; |
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fname = rb_entry(parent, struct fname, rb_hash); |
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|
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/* |
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* If the hash and minor hash match up, then we put |
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* them on a linked list. This rarely happens... |
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*/ |
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if ((new_fn->hash == fname->hash) && |
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(new_fn->minor_hash == fname->minor_hash)) { |
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new_fn->next = fname->next; |
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fname->next = new_fn; |
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return 0; |
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} |
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|
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if (new_fn->hash < fname->hash) |
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p = &(*p)->rb_left; |
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else if (new_fn->hash > fname->hash) |
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p = &(*p)->rb_right; |
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else if (new_fn->minor_hash < fname->minor_hash) |
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p = &(*p)->rb_left; |
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else /* if (new_fn->minor_hash > fname->minor_hash) */ |
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p = &(*p)->rb_right; |
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} |
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|
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rb_link_node(&new_fn->rb_hash, parent, p); |
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rb_insert_color(&new_fn->rb_hash, &info->root); |
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return 0; |
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} |
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|
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|
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/* |
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* This is a helper function for ext4_dx_readdir. It calls filldir |
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* for all entres on the fname linked list. (Normally there is only |
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* one entry on the linked list, unless there are 62 bit hash collisions.) |
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*/ |
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static int call_filldir(struct file *file, struct dir_context *ctx, |
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struct fname *fname) |
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{ |
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struct dir_private_info *info = file->private_data; |
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struct inode *inode = file_inode(file); |
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struct super_block *sb = inode->i_sb; |
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|
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if (!fname) { |
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ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " |
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"called with null fname?!?", __func__, __LINE__, |
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inode->i_ino, current->comm); |
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return 0; |
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} |
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ctx->pos = hash2pos(file, fname->hash, fname->minor_hash); |
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while (fname) { |
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if (!dir_emit(ctx, fname->name, |
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fname->name_len, |
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fname->inode, |
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get_dtype(sb, fname->file_type))) { |
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info->extra_fname = fname; |
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return 1; |
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} |
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fname = fname->next; |
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} |
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return 0; |
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} |
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|
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static int ext4_dx_readdir(struct file *file, struct dir_context *ctx) |
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{ |
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struct dir_private_info *info = file->private_data; |
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struct inode *inode = file_inode(file); |
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struct fname *fname; |
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int ret; |
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|
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if (!info) { |
|
info = ext4_htree_create_dir_info(file, ctx->pos); |
|
if (!info) |
|
return -ENOMEM; |
|
file->private_data = info; |
|
} |
|
|
|
if (ctx->pos == ext4_get_htree_eof(file)) |
|
return 0; /* EOF */ |
|
|
|
/* Some one has messed with f_pos; reset the world */ |
|
if (info->last_pos != ctx->pos) { |
|
free_rb_tree_fname(&info->root); |
|
info->curr_node = NULL; |
|
info->extra_fname = NULL; |
|
info->curr_hash = pos2maj_hash(file, ctx->pos); |
|
info->curr_minor_hash = pos2min_hash(file, ctx->pos); |
|
} |
|
|
|
/* |
|
* If there are any leftover names on the hash collision |
|
* chain, return them first. |
|
*/ |
|
if (info->extra_fname) { |
|
if (call_filldir(file, ctx, info->extra_fname)) |
|
goto finished; |
|
info->extra_fname = NULL; |
|
goto next_node; |
|
} else if (!info->curr_node) |
|
info->curr_node = rb_first(&info->root); |
|
|
|
while (1) { |
|
/* |
|
* Fill the rbtree if we have no more entries, |
|
* or the inode has changed since we last read in the |
|
* cached entries. |
|
*/ |
|
if ((!info->curr_node) || |
|
!inode_eq_iversion(inode, file->f_version)) { |
|
info->curr_node = NULL; |
|
free_rb_tree_fname(&info->root); |
|
file->f_version = inode_query_iversion(inode); |
|
ret = ext4_htree_fill_tree(file, info->curr_hash, |
|
info->curr_minor_hash, |
|
&info->next_hash); |
|
if (ret < 0) |
|
return ret; |
|
if (ret == 0) { |
|
ctx->pos = ext4_get_htree_eof(file); |
|
break; |
|
} |
|
info->curr_node = rb_first(&info->root); |
|
} |
|
|
|
fname = rb_entry(info->curr_node, struct fname, rb_hash); |
|
info->curr_hash = fname->hash; |
|
info->curr_minor_hash = fname->minor_hash; |
|
if (call_filldir(file, ctx, fname)) |
|
break; |
|
next_node: |
|
info->curr_node = rb_next(info->curr_node); |
|
if (info->curr_node) { |
|
fname = rb_entry(info->curr_node, struct fname, |
|
rb_hash); |
|
info->curr_hash = fname->hash; |
|
info->curr_minor_hash = fname->minor_hash; |
|
} else { |
|
if (info->next_hash == ~0) { |
|
ctx->pos = ext4_get_htree_eof(file); |
|
break; |
|
} |
|
info->curr_hash = info->next_hash; |
|
info->curr_minor_hash = 0; |
|
} |
|
} |
|
finished: |
|
info->last_pos = ctx->pos; |
|
return 0; |
|
} |
|
|
|
static int ext4_release_dir(struct inode *inode, struct file *filp) |
|
{ |
|
if (filp->private_data) |
|
ext4_htree_free_dir_info(filp->private_data); |
|
|
|
return 0; |
|
} |
|
|
|
int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf, |
|
int buf_size) |
|
{ |
|
struct ext4_dir_entry_2 *de; |
|
int rlen; |
|
unsigned int offset = 0; |
|
char *top; |
|
|
|
de = (struct ext4_dir_entry_2 *)buf; |
|
top = buf + buf_size; |
|
while ((char *) de < top) { |
|
if (ext4_check_dir_entry(dir, NULL, de, bh, |
|
buf, buf_size, offset)) |
|
return -EFSCORRUPTED; |
|
rlen = ext4_rec_len_from_disk(de->rec_len, buf_size); |
|
de = (struct ext4_dir_entry_2 *)((char *)de + rlen); |
|
offset += rlen; |
|
} |
|
if ((char *) de > top) |
|
return -EFSCORRUPTED; |
|
|
|
return 0; |
|
} |
|
|
|
const struct file_operations ext4_dir_operations = { |
|
.llseek = ext4_dir_llseek, |
|
.read = generic_read_dir, |
|
.iterate_shared = ext4_readdir, |
|
.unlocked_ioctl = ext4_ioctl, |
|
#ifdef CONFIG_COMPAT |
|
.compat_ioctl = ext4_compat_ioctl, |
|
#endif |
|
.fsync = ext4_sync_file, |
|
.release = ext4_release_dir, |
|
};
|
|
|