exofs: dir_inode and directory operations
implementation of directory and inode operations.
* A directory is treated as a file, and essentially contains a list
of <file name, inode #> pairs for files that are found in that
directory. The object IDs correspond to the files' inode numbers
and are allocated using a 64bit incrementing global counter.
* Each file's control block (AKA on-disk inode) is stored in its
object's attributes. This applies to both regular files and other
types (directories, device files, symlinks, etc.).
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
diff --git a/fs/exofs/dir.c b/fs/exofs/dir.c
new file mode 100644
index 0000000..6865605
--- /dev/null
+++ b/fs/exofs/dir.c
@@ -0,0 +1,657 @@
+/*
+ * Copyright (C) 2005, 2006
+ * Avishay Traeger (avishay@gmail.com) (avishay@il.ibm.com)
+ * Copyright (C) 2005, 2006
+ * International Business Machines
+ * Copyright (C) 2008, 2009
+ * Boaz Harrosh <bharrosh@panasas.com>
+ *
+ * Copyrights for code taken from ext2:
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ * from
+ * linux/fs/minix/inode.c
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ *
+ * This file is part of exofs.
+ *
+ * exofs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation. Since it is based on ext2, and the only
+ * valid version of GPL for the Linux kernel is version 2, the only valid
+ * version of GPL for exofs is version 2.
+ *
+ * exofs is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with exofs; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "exofs.h"
+
+static inline unsigned exofs_chunk_size(struct inode *inode)
+{
+ return inode->i_sb->s_blocksize;
+}
+
+static inline void exofs_put_page(struct page *page)
+{
+ kunmap(page);
+ page_cache_release(page);
+}
+
+/* Accesses dir's inode->i_size must be called under inode lock */
+static inline unsigned long dir_pages(struct inode *inode)
+{
+ return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+}
+
+static unsigned exofs_last_byte(struct inode *inode, unsigned long page_nr)
+{
+ loff_t last_byte = inode->i_size;
+
+ last_byte -= page_nr << PAGE_CACHE_SHIFT;
+ if (last_byte > PAGE_CACHE_SIZE)
+ last_byte = PAGE_CACHE_SIZE;
+ return last_byte;
+}
+
+static int exofs_commit_chunk(struct page *page, loff_t pos, unsigned len)
+{
+ struct address_space *mapping = page->mapping;
+ struct inode *dir = mapping->host;
+ int err = 0;
+
+ dir->i_version++;
+
+ if (!PageUptodate(page))
+ SetPageUptodate(page);
+
+ if (pos+len > dir->i_size) {
+ i_size_write(dir, pos+len);
+ mark_inode_dirty(dir);
+ }
+ set_page_dirty(page);
+
+ if (IS_DIRSYNC(dir))
+ err = write_one_page(page, 1);
+ else
+ unlock_page(page);
+
+ return err;
+}
+
+static void exofs_check_page(struct page *page)
+{
+ struct inode *dir = page->mapping->host;
+ unsigned chunk_size = exofs_chunk_size(dir);
+ char *kaddr = page_address(page);
+ unsigned offs, rec_len;
+ unsigned limit = PAGE_CACHE_SIZE;
+ struct exofs_dir_entry *p;
+ char *error;
+
+ /* if the page is the last one in the directory */
+ if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
+ limit = dir->i_size & ~PAGE_CACHE_MASK;
+ if (limit & (chunk_size - 1))
+ goto Ebadsize;
+ if (!limit)
+ goto out;
+ }
+ for (offs = 0; offs <= limit - EXOFS_DIR_REC_LEN(1); offs += rec_len) {
+ p = (struct exofs_dir_entry *)(kaddr + offs);
+ rec_len = le16_to_cpu(p->rec_len);
+
+ if (rec_len < EXOFS_DIR_REC_LEN(1))
+ goto Eshort;
+ if (rec_len & 3)
+ goto Ealign;
+ if (rec_len < EXOFS_DIR_REC_LEN(p->name_len))
+ goto Enamelen;
+ if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
+ goto Espan;
+ }
+ if (offs != limit)
+ goto Eend;
+out:
+ SetPageChecked(page);
+ return;
+
+Ebadsize:
+ EXOFS_ERR("ERROR [exofs_check_page]: "
+ "size of directory #%lu is not a multiple of chunk size",
+ dir->i_ino
+ );
+ goto fail;
+Eshort:
+ error = "rec_len is smaller than minimal";
+ goto bad_entry;
+Ealign:
+ error = "unaligned directory entry";
+ goto bad_entry;
+Enamelen:
+ error = "rec_len is too small for name_len";
+ goto bad_entry;
+Espan:
+ error = "directory entry across blocks";
+ goto bad_entry;
+bad_entry:
+ EXOFS_ERR(
+ "ERROR [exofs_check_page]: bad entry in directory #%lu: %s - "
+ "offset=%lu, inode=%llu, rec_len=%d, name_len=%d",
+ dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
+ _LLU(le64_to_cpu(p->inode_no)),
+ rec_len, p->name_len);
+ goto fail;
+Eend:
+ p = (struct exofs_dir_entry *)(kaddr + offs);
+ EXOFS_ERR("ERROR [exofs_check_page]: "
+ "entry in directory #%lu spans the page boundary"
+ "offset=%lu, inode=%llu",
+ dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
+ _LLU(le64_to_cpu(p->inode_no)));
+fail:
+ SetPageChecked(page);
+ SetPageError(page);
+}
+
+static struct page *exofs_get_page(struct inode *dir, unsigned long n)
+{
+ struct address_space *mapping = dir->i_mapping;
+ struct page *page = read_mapping_page(mapping, n, NULL);
+
+ if (!IS_ERR(page)) {
+ kmap(page);
+ if (!PageChecked(page))
+ exofs_check_page(page);
+ if (PageError(page))
+ goto fail;
+ }
+ return page;
+
+fail:
+ exofs_put_page(page);
+ return ERR_PTR(-EIO);
+}
+
+static inline int exofs_match(int len, const unsigned char *name,
+ struct exofs_dir_entry *de)
+{
+ if (len != de->name_len)
+ return 0;
+ if (!de->inode_no)
+ return 0;
+ return !memcmp(name, de->name, len);
+}
+
+static inline
+struct exofs_dir_entry *exofs_next_entry(struct exofs_dir_entry *p)
+{
+ return (struct exofs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
+}
+
+static inline unsigned
+exofs_validate_entry(char *base, unsigned offset, unsigned mask)
+{
+ struct exofs_dir_entry *de = (struct exofs_dir_entry *)(base + offset);
+ struct exofs_dir_entry *p =
+ (struct exofs_dir_entry *)(base + (offset&mask));
+ while ((char *)p < (char *)de) {
+ if (p->rec_len == 0)
+ break;
+ p = exofs_next_entry(p);
+ }
+ return (char *)p - base;
+}
+
+static unsigned char exofs_filetype_table[EXOFS_FT_MAX] = {
+ [EXOFS_FT_UNKNOWN] = DT_UNKNOWN,
+ [EXOFS_FT_REG_FILE] = DT_REG,
+ [EXOFS_FT_DIR] = DT_DIR,
+ [EXOFS_FT_CHRDEV] = DT_CHR,
+ [EXOFS_FT_BLKDEV] = DT_BLK,
+ [EXOFS_FT_FIFO] = DT_FIFO,
+ [EXOFS_FT_SOCK] = DT_SOCK,
+ [EXOFS_FT_SYMLINK] = DT_LNK,
+};
+
+#define S_SHIFT 12
+static unsigned char exofs_type_by_mode[S_IFMT >> S_SHIFT] = {
+ [S_IFREG >> S_SHIFT] = EXOFS_FT_REG_FILE,
+ [S_IFDIR >> S_SHIFT] = EXOFS_FT_DIR,
+ [S_IFCHR >> S_SHIFT] = EXOFS_FT_CHRDEV,
+ [S_IFBLK >> S_SHIFT] = EXOFS_FT_BLKDEV,
+ [S_IFIFO >> S_SHIFT] = EXOFS_FT_FIFO,
+ [S_IFSOCK >> S_SHIFT] = EXOFS_FT_SOCK,
+ [S_IFLNK >> S_SHIFT] = EXOFS_FT_SYMLINK,
+};
+
+static inline
+void exofs_set_de_type(struct exofs_dir_entry *de, struct inode *inode)
+{
+ mode_t mode = inode->i_mode;
+ de->file_type = exofs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
+}
+
+static int
+exofs_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+ loff_t pos = filp->f_pos;
+ struct inode *inode = filp->f_path.dentry->d_inode;
+ unsigned int offset = pos & ~PAGE_CACHE_MASK;
+ unsigned long n = pos >> PAGE_CACHE_SHIFT;
+ unsigned long npages = dir_pages(inode);
+ unsigned chunk_mask = ~(exofs_chunk_size(inode)-1);
+ unsigned char *types = NULL;
+ int need_revalidate = (filp->f_version != inode->i_version);
+
+ if (pos > inode->i_size - EXOFS_DIR_REC_LEN(1))
+ return 0;
+
+ types = exofs_filetype_table;
+
+ for ( ; n < npages; n++, offset = 0) {
+ char *kaddr, *limit;
+ struct exofs_dir_entry *de;
+ struct page *page = exofs_get_page(inode, n);
+
+ if (IS_ERR(page)) {
+ EXOFS_ERR("ERROR: "
+ "bad page in #%lu",
+ inode->i_ino);
+ filp->f_pos += PAGE_CACHE_SIZE - offset;
+ return PTR_ERR(page);
+ }
+ kaddr = page_address(page);
+ if (unlikely(need_revalidate)) {
+ if (offset) {
+ offset = exofs_validate_entry(kaddr, offset,
+ chunk_mask);
+ filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
+ }
+ filp->f_version = inode->i_version;
+ need_revalidate = 0;
+ }
+ de = (struct exofs_dir_entry *)(kaddr + offset);
+ limit = kaddr + exofs_last_byte(inode, n) -
+ EXOFS_DIR_REC_LEN(1);
+ for (; (char *)de <= limit; de = exofs_next_entry(de)) {
+ if (de->rec_len == 0) {
+ EXOFS_ERR("ERROR: "
+ "zero-length directory entry");
+ exofs_put_page(page);
+ return -EIO;
+ }
+ if (de->inode_no) {
+ int over;
+ unsigned char d_type = DT_UNKNOWN;
+
+ if (types && de->file_type < EXOFS_FT_MAX)
+ d_type = types[de->file_type];
+
+ offset = (char *)de - kaddr;
+ over = filldir(dirent, de->name, de->name_len,
+ (n<<PAGE_CACHE_SHIFT) | offset,
+ le64_to_cpu(de->inode_no),
+ d_type);
+ if (over) {
+ exofs_put_page(page);
+ return 0;
+ }
+ }
+ filp->f_pos += le16_to_cpu(de->rec_len);
+ }
+ exofs_put_page(page);
+ }
+
+ return 0;
+}
+
+struct exofs_dir_entry *exofs_find_entry(struct inode *dir,
+ struct dentry *dentry, struct page **res_page)
+{
+ const unsigned char *name = dentry->d_name.name;
+ int namelen = dentry->d_name.len;
+ unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
+ unsigned long start, n;
+ unsigned long npages = dir_pages(dir);
+ struct page *page = NULL;
+ struct exofs_i_info *oi = exofs_i(dir);
+ struct exofs_dir_entry *de;
+
+ if (npages == 0)
+ goto out;
+
+ *res_page = NULL;
+
+ start = oi->i_dir_start_lookup;
+ if (start >= npages)
+ start = 0;
+ n = start;
+ do {
+ char *kaddr;
+ page = exofs_get_page(dir, n);
+ if (!IS_ERR(page)) {
+ kaddr = page_address(page);
+ de = (struct exofs_dir_entry *) kaddr;
+ kaddr += exofs_last_byte(dir, n) - reclen;
+ while ((char *) de <= kaddr) {
+ if (de->rec_len == 0) {
+ EXOFS_ERR(
+ "ERROR: exofs_find_entry: "
+ "zero-length directory entry");
+ exofs_put_page(page);
+ goto out;
+ }
+ if (exofs_match(namelen, name, de))
+ goto found;
+ de = exofs_next_entry(de);
+ }
+ exofs_put_page(page);
+ }
+ if (++n >= npages)
+ n = 0;
+ } while (n != start);
+out:
+ return NULL;
+
+found:
+ *res_page = page;
+ oi->i_dir_start_lookup = n;
+ return de;
+}
+
+struct exofs_dir_entry *exofs_dotdot(struct inode *dir, struct page **p)
+{
+ struct page *page = exofs_get_page(dir, 0);
+ struct exofs_dir_entry *de = NULL;
+
+ if (!IS_ERR(page)) {
+ de = exofs_next_entry(
+ (struct exofs_dir_entry *)page_address(page));
+ *p = page;
+ }
+ return de;
+}
+
+ino_t exofs_inode_by_name(struct inode *dir, struct dentry *dentry)
+{
+ ino_t res = 0;
+ struct exofs_dir_entry *de;
+ struct page *page;
+
+ de = exofs_find_entry(dir, dentry, &page);
+ if (de) {
+ res = le64_to_cpu(de->inode_no);
+ exofs_put_page(page);
+ }
+ return res;
+}
+
+int exofs_set_link(struct inode *dir, struct exofs_dir_entry *de,
+ struct page *page, struct inode *inode)
+{
+ loff_t pos = page_offset(page) +
+ (char *) de - (char *) page_address(page);
+ unsigned len = le16_to_cpu(de->rec_len);
+ int err;
+
+ lock_page(page);
+ err = exofs_write_begin(NULL, page->mapping, pos, len,
+ AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
+ if (err)
+ EXOFS_ERR("exofs_set_link: exofs_write_begin FAILD => %d\n",
+ err);
+
+ de->inode_no = cpu_to_le64(inode->i_ino);
+ exofs_set_de_type(de, inode);
+ if (likely(!err))
+ err = exofs_commit_chunk(page, pos, len);
+ exofs_put_page(page);
+ dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+ mark_inode_dirty(dir);
+ return err;
+}
+
+int exofs_add_link(struct dentry *dentry, struct inode *inode)
+{
+ struct inode *dir = dentry->d_parent->d_inode;
+ const unsigned char *name = dentry->d_name.name;
+ int namelen = dentry->d_name.len;
+ unsigned chunk_size = exofs_chunk_size(dir);
+ unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
+ unsigned short rec_len, name_len;
+ struct page *page = NULL;
+ struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
+ struct exofs_dir_entry *de;
+ unsigned long npages = dir_pages(dir);
+ unsigned long n;
+ char *kaddr;
+ loff_t pos;
+ int err;
+
+ for (n = 0; n <= npages; n++) {
+ char *dir_end;
+
+ page = exofs_get_page(dir, n);
+ err = PTR_ERR(page);
+ if (IS_ERR(page))
+ goto out;
+ lock_page(page);
+ kaddr = page_address(page);
+ dir_end = kaddr + exofs_last_byte(dir, n);
+ de = (struct exofs_dir_entry *)kaddr;
+ kaddr += PAGE_CACHE_SIZE - reclen;
+ while ((char *)de <= kaddr) {
+ if ((char *)de == dir_end) {
+ name_len = 0;
+ rec_len = chunk_size;
+ de->rec_len = cpu_to_le16(chunk_size);
+ de->inode_no = 0;
+ goto got_it;
+ }
+ if (de->rec_len == 0) {
+ EXOFS_ERR("ERROR: exofs_add_link: "
+ "zero-length directory entry");
+ err = -EIO;
+ goto out_unlock;
+ }
+ err = -EEXIST;
+ if (exofs_match(namelen, name, de))
+ goto out_unlock;
+ name_len = EXOFS_DIR_REC_LEN(de->name_len);
+ rec_len = le16_to_cpu(de->rec_len);
+ if (!de->inode_no && rec_len >= reclen)
+ goto got_it;
+ if (rec_len >= name_len + reclen)
+ goto got_it;
+ de = (struct exofs_dir_entry *) ((char *) de + rec_len);
+ }
+ unlock_page(page);
+ exofs_put_page(page);
+ }
+
+ EXOFS_ERR("exofs_add_link: BAD dentry=%p or inode=%p", dentry, inode);
+ return -EINVAL;
+
+got_it:
+ pos = page_offset(page) +
+ (char *)de - (char *)page_address(page);
+ err = exofs_write_begin(NULL, page->mapping, pos, rec_len, 0,
+ &page, NULL);
+ if (err)
+ goto out_unlock;
+ if (de->inode_no) {
+ struct exofs_dir_entry *de1 =
+ (struct exofs_dir_entry *)((char *)de + name_len);
+ de1->rec_len = cpu_to_le16(rec_len - name_len);
+ de->rec_len = cpu_to_le16(name_len);
+ de = de1;
+ }
+ de->name_len = namelen;
+ memcpy(de->name, name, namelen);
+ de->inode_no = cpu_to_le64(inode->i_ino);
+ exofs_set_de_type(de, inode);
+ err = exofs_commit_chunk(page, pos, rec_len);
+ dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+ mark_inode_dirty(dir);
+ sbi->s_numfiles++;
+
+out_put:
+ exofs_put_page(page);
+out:
+ return err;
+out_unlock:
+ unlock_page(page);
+ goto out_put;
+}
+
+int exofs_delete_entry(struct exofs_dir_entry *dir, struct page *page)
+{
+ struct address_space *mapping = page->mapping;
+ struct inode *inode = mapping->host;
+ struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
+ char *kaddr = page_address(page);
+ unsigned from = ((char *)dir - kaddr) & ~(exofs_chunk_size(inode)-1);
+ unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
+ loff_t pos;
+ struct exofs_dir_entry *pde = NULL;
+ struct exofs_dir_entry *de = (struct exofs_dir_entry *) (kaddr + from);
+ int err;
+
+ while (de < dir) {
+ if (de->rec_len == 0) {
+ EXOFS_ERR("ERROR: exofs_delete_entry:"
+ "zero-length directory entry");
+ err = -EIO;
+ goto out;
+ }
+ pde = de;
+ de = exofs_next_entry(de);
+ }
+ if (pde)
+ from = (char *)pde - (char *)page_address(page);
+ pos = page_offset(page) + from;
+ lock_page(page);
+ err = exofs_write_begin(NULL, page->mapping, pos, to - from, 0,
+ &page, NULL);
+ if (err)
+ EXOFS_ERR("exofs_delete_entry: exofs_write_begin FAILD => %d\n",
+ err);
+ if (pde)
+ pde->rec_len = cpu_to_le16(to - from);
+ dir->inode_no = 0;
+ if (likely(!err))
+ err = exofs_commit_chunk(page, pos, to - from);
+ inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+ mark_inode_dirty(inode);
+ sbi->s_numfiles--;
+out:
+ exofs_put_page(page);
+ return err;
+}
+
+/* kept aligned on 4 bytes */
+#define THIS_DIR ".\0\0"
+#define PARENT_DIR "..\0"
+
+int exofs_make_empty(struct inode *inode, struct inode *parent)
+{
+ struct address_space *mapping = inode->i_mapping;
+ struct page *page = grab_cache_page(mapping, 0);
+ unsigned chunk_size = exofs_chunk_size(inode);
+ struct exofs_dir_entry *de;
+ int err;
+ void *kaddr;
+
+ if (!page)
+ return -ENOMEM;
+
+ err = exofs_write_begin(NULL, page->mapping, 0, chunk_size, 0,
+ &page, NULL);
+ if (err) {
+ unlock_page(page);
+ goto fail;
+ }
+
+ kaddr = kmap_atomic(page, KM_USER0);
+ de = (struct exofs_dir_entry *)kaddr;
+ de->name_len = 1;
+ de->rec_len = cpu_to_le16(EXOFS_DIR_REC_LEN(1));
+ memcpy(de->name, THIS_DIR, sizeof(THIS_DIR));
+ de->inode_no = cpu_to_le64(inode->i_ino);
+ exofs_set_de_type(de, inode);
+
+ de = (struct exofs_dir_entry *)(kaddr + EXOFS_DIR_REC_LEN(1));
+ de->name_len = 2;
+ de->rec_len = cpu_to_le16(chunk_size - EXOFS_DIR_REC_LEN(1));
+ de->inode_no = cpu_to_le64(parent->i_ino);
+ memcpy(de->name, PARENT_DIR, sizeof(PARENT_DIR));
+ exofs_set_de_type(de, inode);
+ kunmap_atomic(page, KM_USER0);
+ err = exofs_commit_chunk(page, 0, chunk_size);
+fail:
+ page_cache_release(page);
+ return err;
+}
+
+int exofs_empty_dir(struct inode *inode)
+{
+ struct page *page = NULL;
+ unsigned long i, npages = dir_pages(inode);
+
+ for (i = 0; i < npages; i++) {
+ char *kaddr;
+ struct exofs_dir_entry *de;
+ page = exofs_get_page(inode, i);
+
+ if (IS_ERR(page))
+ continue;
+
+ kaddr = page_address(page);
+ de = (struct exofs_dir_entry *)kaddr;
+ kaddr += exofs_last_byte(inode, i) - EXOFS_DIR_REC_LEN(1);
+
+ while ((char *)de <= kaddr) {
+ if (de->rec_len == 0) {
+ EXOFS_ERR("ERROR: exofs_empty_dir: "
+ "zero-length directory entry"
+ "kaddr=%p, de=%p\n", kaddr, de);
+ goto not_empty;
+ }
+ if (de->inode_no != 0) {
+ /* check for . and .. */
+ if (de->name[0] != '.')
+ goto not_empty;
+ if (de->name_len > 2)
+ goto not_empty;
+ if (de->name_len < 2) {
+ if (le64_to_cpu(de->inode_no) !=
+ inode->i_ino)
+ goto not_empty;
+ } else if (de->name[1] != '.')
+ goto not_empty;
+ }
+ de = exofs_next_entry(de);
+ }
+ exofs_put_page(page);
+ }
+ return 1;
+
+not_empty:
+ exofs_put_page(page);
+ return 0;
+}
+
+const struct file_operations exofs_dir_operations = {
+ .llseek = generic_file_llseek,
+ .read = generic_read_dir,
+ .readdir = exofs_readdir,
+};