Commit aa4f3f28 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

[PATCH] ext2 directory handling

Convert ext2 directory handling to not rely on the contents of pages
outside i_size.

This is because block_write_full_page (which is used for all writeback)
zaps the page outside i_size.
parent 63b060c4
...@@ -46,6 +46,21 @@ static inline unsigned long dir_pages(struct inode *inode) ...@@ -46,6 +46,21 @@ static inline unsigned long dir_pages(struct inode *inode)
return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT; return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
} }
/*
* Return the offset into page `page_nr' of the last valid
* byte in that page, plus one.
*/
static unsigned
ext2_last_byte(struct inode *inode, unsigned long page_nr)
{
unsigned 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 ext2_commit_chunk(struct page *page, unsigned from, unsigned to) static int ext2_commit_chunk(struct page *page, unsigned from, unsigned to)
{ {
struct inode *dir = page->mapping->host; struct inode *dir = page->mapping->host;
...@@ -78,10 +93,6 @@ static void ext2_check_page(struct page *page) ...@@ -78,10 +93,6 @@ static void ext2_check_page(struct page *page)
limit = dir->i_size & ~PAGE_CACHE_MASK; limit = dir->i_size & ~PAGE_CACHE_MASK;
if (limit & (chunk_size - 1)) if (limit & (chunk_size - 1))
goto Ebadsize; goto Ebadsize;
for (offs = limit; offs<PAGE_CACHE_SIZE; offs += chunk_size) {
ext2_dirent *p = (ext2_dirent*)(kaddr + offs);
p->rec_len = cpu_to_le16(chunk_size);
}
if (!limit) if (!limit)
goto out; goto out;
} }
...@@ -197,8 +208,11 @@ ext2_validate_entry(char *base, unsigned offset, unsigned mask) ...@@ -197,8 +208,11 @@ ext2_validate_entry(char *base, unsigned offset, unsigned mask)
{ {
ext2_dirent *de = (ext2_dirent*)(base + offset); ext2_dirent *de = (ext2_dirent*)(base + offset);
ext2_dirent *p = (ext2_dirent*)(base + (offset&mask)); ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
while ((char*)p < (char*)de) while ((char*)p < (char*)de) {
if (p->rec_len == 0)
break;
p = ext2_next_entry(p); p = ext2_next_entry(p);
}
return (char *)p - base; return (char *)p - base;
} }
...@@ -245,6 +259,7 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir) ...@@ -245,6 +259,7 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
unsigned chunk_mask = ~(ext2_chunk_size(inode)-1); unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
unsigned char *types = NULL; unsigned char *types = NULL;
int need_revalidate = (filp->f_version != inode->i_version); int need_revalidate = (filp->f_version != inode->i_version);
int ret = 0;
if (pos > inode->i_size - EXT2_DIR_REC_LEN(1)) if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
goto done; goto done;
...@@ -265,8 +280,15 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir) ...@@ -265,8 +280,15 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
need_revalidate = 0; need_revalidate = 0;
} }
de = (ext2_dirent *)(kaddr+offset); de = (ext2_dirent *)(kaddr+offset);
limit = kaddr + PAGE_CACHE_SIZE - EXT2_DIR_REC_LEN(1); limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
for ( ;(char*)de <= limit; de = ext2_next_entry(de)) for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
if (de->rec_len == 0) {
ext2_error(sb, __FUNCTION__,
"zero-length directory entry");
ret = -EIO;
ext2_put_page(page);
goto done;
}
if (de->inode) { if (de->inode) {
int over; int over;
unsigned char d_type = DT_UNKNOWN; unsigned char d_type = DT_UNKNOWN;
...@@ -283,6 +305,7 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir) ...@@ -283,6 +305,7 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
goto done; goto done;
} }
} }
}
ext2_put_page(page); ext2_put_page(page);
} }
...@@ -326,8 +349,14 @@ struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir, ...@@ -326,8 +349,14 @@ struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
if (!IS_ERR(page)) { if (!IS_ERR(page)) {
kaddr = page_address(page); kaddr = page_address(page);
de = (ext2_dirent *) kaddr; de = (ext2_dirent *) kaddr;
kaddr += PAGE_CACHE_SIZE - reclen; kaddr += ext2_last_byte(dir, n) - reclen;
while ((char *) de <= kaddr) { while ((char *) de <= kaddr) {
if (de->rec_len == 0) {
ext2_error(dir->i_sb, __FUNCTION__,
"zero-length directory entry");
ext2_put_page(page);
goto out;
}
if (ext2_match (namelen, name, de)) if (ext2_match (namelen, name, de))
goto found; goto found;
de = ext2_next_entry(de); de = ext2_next_entry(de);
...@@ -337,6 +366,7 @@ struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir, ...@@ -337,6 +366,7 @@ struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
if (++n >= npages) if (++n >= npages)
n = 0; n = 0;
} while (n != start); } while (n != start);
out:
return NULL; return NULL;
found: found:
...@@ -401,6 +431,7 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode) ...@@ -401,6 +431,7 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
struct inode *dir = dentry->d_parent->d_inode; struct inode *dir = dentry->d_parent->d_inode;
const char *name = dentry->d_name.name; const char *name = dentry->d_name.name;
int namelen = dentry->d_name.len; int namelen = dentry->d_name.len;
unsigned chunk_size = ext2_chunk_size(dir);
unsigned reclen = EXT2_DIR_REC_LEN(namelen); unsigned reclen = EXT2_DIR_REC_LEN(namelen);
unsigned short rec_len, name_len; unsigned short rec_len, name_len;
struct page *page = NULL; struct page *page = NULL;
...@@ -411,19 +442,41 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode) ...@@ -411,19 +442,41 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
unsigned from, to; unsigned from, to;
int err; int err;
/* We take care of directory expansion in the same loop */ /*
* We take care of directory expansion in the same loop.
* This code plays outside i_size, so it locks the page
* to protect that region.
*/
for (n = 0; n <= npages; n++) { for (n = 0; n <= npages; n++) {
char *dir_end;
page = ext2_get_page(dir, n); page = ext2_get_page(dir, n);
err = PTR_ERR(page); err = PTR_ERR(page);
if (IS_ERR(page)) if (IS_ERR(page))
goto out; goto out;
lock_page(page);
kaddr = page_address(page); kaddr = page_address(page);
dir_end = kaddr + ext2_last_byte(dir, n);
de = (ext2_dirent *)kaddr; de = (ext2_dirent *)kaddr;
kaddr += PAGE_CACHE_SIZE - reclen; kaddr += PAGE_CACHE_SIZE - reclen;
while ((char *)de <= kaddr) { while ((char *)de <= kaddr) {
if ((char *)de == dir_end) {
/* We hit i_size */
name_len = 0;
rec_len = chunk_size;
de->rec_len = cpu_to_le16(chunk_size);
de->inode = 0;
goto got_it;
}
if (de->rec_len == 0) {
ext2_error(dir->i_sb, __FUNCTION__,
"zero-length directory entry");
err = -EIO;
goto out_unlock;
}
err = -EEXIST; err = -EEXIST;
if (ext2_match (namelen, name, de)) if (ext2_match (namelen, name, de))
goto out_page; goto out_unlock;
name_len = EXT2_DIR_REC_LEN(de->name_len); name_len = EXT2_DIR_REC_LEN(de->name_len);
rec_len = le16_to_cpu(de->rec_len); rec_len = le16_to_cpu(de->rec_len);
if (!de->inode && rec_len >= reclen) if (!de->inode && rec_len >= reclen)
...@@ -432,6 +485,7 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode) ...@@ -432,6 +485,7 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
goto got_it; goto got_it;
de = (ext2_dirent *) ((char *) de + rec_len); de = (ext2_dirent *) ((char *) de + rec_len);
} }
unlock_page(page);
ext2_put_page(page); ext2_put_page(page);
} }
BUG(); BUG();
...@@ -440,7 +494,6 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode) ...@@ -440,7 +494,6 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
got_it: got_it:
from = (char*)de - (char*)page_address(page); from = (char*)de - (char*)page_address(page);
to = from + rec_len; to = from + rec_len;
lock_page(page);
err = page->mapping->a_ops->prepare_write(NULL, page, from, to); err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
if (err) if (err)
goto out_unlock; goto out_unlock;
...@@ -460,7 +513,6 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode) ...@@ -460,7 +513,6 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
/* OFFSET_CACHE */ /* OFFSET_CACHE */
out_unlock: out_unlock:
UnlockPage(page); UnlockPage(page);
out_page:
ext2_put_page(page); ext2_put_page(page);
out: out:
return err; return err;
...@@ -482,6 +534,12 @@ int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page ) ...@@ -482,6 +534,12 @@ int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
int err; int err;
while ((char*)de < (char*)dir) { while ((char*)de < (char*)dir) {
if (de->rec_len == 0) {
ext2_error(inode->i_sb, __FUNCTION__,
"zero-length directory entry");
err = -EIO;
goto out;
}
pde = de; pde = de;
de = ext2_next_entry(de); de = ext2_next_entry(de);
} }
...@@ -496,9 +554,10 @@ int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page ) ...@@ -496,9 +554,10 @@ int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
dir->inode = 0; dir->inode = 0;
err = ext2_commit_chunk(page, from, to); err = ext2_commit_chunk(page, from, to);
UnlockPage(page); UnlockPage(page);
ext2_put_page(page);
inode->i_ctime = inode->i_mtime = CURRENT_TIME; inode->i_ctime = inode->i_mtime = CURRENT_TIME;
mark_inode_dirty(inode); mark_inode_dirty(inode);
out:
ext2_put_page(page);
return err; return err;
} }
...@@ -561,9 +620,15 @@ int ext2_empty_dir (struct inode * inode) ...@@ -561,9 +620,15 @@ int ext2_empty_dir (struct inode * inode)
kaddr = page_address(page); kaddr = page_address(page);
de = (ext2_dirent *)kaddr; de = (ext2_dirent *)kaddr;
kaddr += PAGE_CACHE_SIZE-EXT2_DIR_REC_LEN(1); kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
while ((char *)de <= kaddr) { while ((char *)de <= kaddr) {
if (de->rec_len == 0) {
ext2_error(inode->i_sb, __FUNCTION__,
"zero-length directory entry");
printk("kaddr=%p, de=%p\n", kaddr, de);
goto not_empty;
}
if (de->inode != 0) { if (de->inode != 0) {
/* check for . and .. */ /* check for . and .. */
if (de->name[0] != '.') if (de->name[0] != '.')
......
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