freevxfs: refactor readdir and lookup code
This change fixes also a buffer overflow which was caused by accessing address space beyond mapped page Signed-off-by: Krzysztof Błaszkowski <kb@sysmikro.com.pl> Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Krzysztof Błaszkowski
Christoph Hellwig
parent
f2fe2fa1fb
commit
12495ea3ac
@ -62,35 +62,6 @@ const struct file_operations vxfs_dir_operations = {
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.iterate_shared = vxfs_readdir,
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};
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static inline u_long
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dir_blocks(struct inode *ip)
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{
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u_long bsize = ip->i_sb->s_blocksize;
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return (ip->i_size + bsize - 1) & ~(bsize - 1);
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}
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/*
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* NOTE! unlike strncmp, vxfs_match returns 1 for success, 0 for failure.
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*
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* len <= VXFS_NAMELEN and de != NULL are guaranteed by caller.
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*/
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static inline int
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vxfs_match(struct vxfs_sb_info *sbi, int len, const char *const name,
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struct vxfs_direct *de)
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{
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if (len != fs16_to_cpu(sbi, de->d_namelen))
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return 0;
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if (!de->d_ino)
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return 0;
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return !memcmp(name, de->d_name, len);
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}
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static inline struct vxfs_direct *
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vxfs_next_entry(struct vxfs_sb_info *sbi, struct vxfs_direct *de)
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{
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return ((struct vxfs_direct *)
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((char *)de + fs16_to_cpu(sbi, de->d_reclen)));
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}
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/**
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* vxfs_find_entry - find a mathing directory entry for a dentry
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@ -109,53 +80,64 @@ vxfs_next_entry(struct vxfs_sb_info *sbi, struct vxfs_direct *de)
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static struct vxfs_direct *
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vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
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{
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struct vxfs_sb_info *sbi = VXFS_SBI(ip->i_sb);
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u_long npages, page, nblocks, pblocks, block;
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u_long bsize = ip->i_sb->s_blocksize;
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const char *name = dp->d_name.name;
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int namelen = dp->d_name.len;
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u_long bsize = ip->i_sb->s_blocksize;
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const char *name = dp->d_name.name;
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int namelen = dp->d_name.len;
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loff_t limit = VXFS_DIRROUND(ip->i_size);
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struct vxfs_direct *de_exit = NULL;
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loff_t pos = 0;
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struct vxfs_sb_info *sbi = VXFS_SBI(ip->i_sb);
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npages = dir_pages(ip);
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nblocks = dir_blocks(ip);
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pblocks = VXFS_BLOCK_PER_PAGE(ip->i_sb);
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for (page = 0; page < npages; page++) {
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caddr_t kaddr;
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struct page *pp;
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while (pos < limit) {
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struct page *pp;
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char *kaddr;
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int pg_ofs = pos & ~PAGE_MASK;
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pp = vxfs_get_page(ip->i_mapping, page);
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pp = vxfs_get_page(ip->i_mapping, pos >> PAGE_SHIFT);
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if (IS_ERR(pp))
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continue;
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kaddr = (caddr_t)page_address(pp);
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return NULL;
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kaddr = (char *)page_address(pp);
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for (block = 0; block <= nblocks && block <= pblocks; block++) {
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caddr_t baddr, limit;
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struct vxfs_dirblk *dbp;
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struct vxfs_direct *de;
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while (pg_ofs < PAGE_SIZE && pos < limit) {
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struct vxfs_direct *de;
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baddr = kaddr + (block * bsize);
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limit = baddr + bsize - VXFS_DIRLEN(1);
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dbp = (struct vxfs_dirblk *)baddr;
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de = (struct vxfs_direct *)
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(baddr + VXFS_DIRBLKOV(sbi, dbp));
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if ((pos & (bsize - 1)) < 4) {
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struct vxfs_dirblk *dbp =
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(struct vxfs_dirblk *)
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(kaddr + (pos & ~PAGE_MASK));
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int overhead = VXFS_DIRBLKOV(sbi, dbp);
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for (; (caddr_t)de <= limit;
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de = vxfs_next_entry(sbi, de)) {
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if (!de->d_reclen)
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break;
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if (!de->d_ino)
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continue;
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if (vxfs_match(sbi, namelen, name, de)) {
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*ppp = pp;
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return (de);
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}
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pos += overhead;
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pg_ofs += overhead;
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}
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de = (struct vxfs_direct *)(kaddr + pg_ofs);
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if (!de->d_reclen) {
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pos += bsize - 1;
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pos &= ~(bsize - 1);
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break;
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}
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pg_ofs += fs16_to_cpu(sbi, de->d_reclen);
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pos += fs16_to_cpu(sbi, de->d_reclen);
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if (!de->d_ino)
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continue;
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if (namelen != fs16_to_cpu(sbi, de->d_namelen))
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continue;
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if (!memcmp(name, de->d_name, namelen)) {
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*ppp = pp;
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de_exit = de;
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break;
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}
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}
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vxfs_put_page(pp);
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if (!de_exit)
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vxfs_put_page(pp);
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else
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break;
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}
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return NULL;
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return de_exit;
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}
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/**
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@ -238,80 +220,81 @@ vxfs_readdir(struct file *fp, struct dir_context *ctx)
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{
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struct inode *ip = file_inode(fp);
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struct super_block *sbp = ip->i_sb;
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struct vxfs_sb_info *sbi = VXFS_SBI(sbp);
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u_long bsize = sbp->s_blocksize;
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u_long page, npages, block, pblocks, nblocks, offset;
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loff_t pos;
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loff_t pos, limit;
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struct vxfs_sb_info *sbi = VXFS_SBI(sbp);
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if (ctx->pos == 0) {
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if (!dir_emit_dot(fp, ctx))
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return 0;
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ctx->pos = 1;
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goto out;
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ctx->pos++;
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}
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if (ctx->pos == 1) {
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if (!dir_emit(ctx, "..", 2, VXFS_INO(ip)->vii_dotdot, DT_DIR))
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return 0;
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ctx->pos = 2;
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goto out;
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ctx->pos++;
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}
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pos = ctx->pos - 2;
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if (pos > VXFS_DIRROUND(ip->i_size))
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return 0;
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npages = dir_pages(ip);
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nblocks = dir_blocks(ip);
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pblocks = VXFS_BLOCK_PER_PAGE(sbp);
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limit = VXFS_DIRROUND(ip->i_size);
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if (ctx->pos > limit)
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goto out;
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page = pos >> PAGE_SHIFT;
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offset = pos & ~PAGE_MASK;
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block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;
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pos = ctx->pos & ~3L;
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for (; page < npages; page++, block = 0) {
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char *kaddr;
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struct page *pp;
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while (pos < limit) {
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struct page *pp;
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char *kaddr;
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int pg_ofs = pos & ~PAGE_MASK;
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int rc = 0;
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pp = vxfs_get_page(ip->i_mapping, page);
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pp = vxfs_get_page(ip->i_mapping, pos >> PAGE_SHIFT);
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if (IS_ERR(pp))
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continue;
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return -ENOMEM;
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kaddr = (char *)page_address(pp);
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for (; block <= nblocks && block <= pblocks; block++) {
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char *baddr, *limit;
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struct vxfs_dirblk *dbp;
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struct vxfs_direct *de;
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while (pg_ofs < PAGE_SIZE && pos < limit) {
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struct vxfs_direct *de;
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baddr = kaddr + (block * bsize);
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limit = baddr + bsize - VXFS_DIRLEN(1);
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dbp = (struct vxfs_dirblk *)baddr;
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de = (struct vxfs_direct *)
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(offset ?
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(kaddr + offset) :
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(baddr + VXFS_DIRBLKOV(sbi, dbp)));
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if ((pos & (bsize - 1)) < 4) {
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struct vxfs_dirblk *dbp =
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(struct vxfs_dirblk *)
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(kaddr + (pos & ~PAGE_MASK));
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int overhead = VXFS_DIRBLKOV(sbi, dbp);
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for (; (char *)de <= limit;
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de = vxfs_next_entry(sbi, de)) {
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if (!de->d_reclen)
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break;
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if (!de->d_ino)
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continue;
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offset = (char *)de - kaddr;
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ctx->pos = ((page << PAGE_SHIFT) | offset) + 2;
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if (!dir_emit(ctx, de->d_name,
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fs16_to_cpu(sbi, de->d_namelen),
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fs32_to_cpu(sbi, de->d_ino),
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DT_UNKNOWN)) {
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vxfs_put_page(pp);
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return 0;
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}
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pos += overhead;
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pg_ofs += overhead;
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}
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de = (struct vxfs_direct *)(kaddr + pg_ofs);
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if (!de->d_reclen) {
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pos += bsize - 1;
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pos &= ~(bsize - 1);
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break;
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}
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pg_ofs += fs16_to_cpu(sbi, de->d_reclen);
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pos += fs16_to_cpu(sbi, de->d_reclen);
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if (!de->d_ino)
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continue;
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rc = dir_emit(ctx, de->d_name,
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fs16_to_cpu(sbi, de->d_namelen),
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fs32_to_cpu(sbi, de->d_ino),
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DT_UNKNOWN);
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if (!rc) {
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/* the dir entry was not read, fix pos. */
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pos -= fs16_to_cpu(sbi, de->d_reclen);
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break;
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}
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offset = 0;
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}
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vxfs_put_page(pp);
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offset = 0;
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if (!rc)
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break;
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}
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ctx->pos = ((page << PAGE_SHIFT) | offset) + 2;
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ctx->pos = pos | 2;
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out:
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return 0;
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}
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