ext2: avoid printk floods in the face of directory corruption

A very large directory with many read failures (either due to storage
problems, or due to invalid size & blocks from corruption) will generate a
printk storm as the filesystem continues to try to read all the blocks.
This flood of messages can tie up the box until it is complete - which may
be a very long time, especially for very large corrupted values.

This is fixed by only reporting the corruption once each time we try to
read the directory.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Eugene Teo <eugeneteo@kernel.sg>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 35 insertions, 25 deletions

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index a78c6b4af06..11a49ce8439 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -103,7 +103,7 @@ static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
         return err;
 }
 
-static void ext2_check_page(struct page *page)
+static void ext2_check_page(struct page *page, int quiet)
 {
         struct inode *dir = page->mapping->host;
         struct super_block *sb = dir->i_sb;
@@ -146,10 +146,10 @@ out:
         /* Too bad, we had an error */
 
 Ebadsize:
-        ext2_error(sb, "ext2_check_page",
-                "size of directory #%lu is not a multiple of chunk size",
-                dir->i_ino
-        );
+        if (!quiet)
+                ext2_error(sb, __func__,
+                        "size of directory #%lu is not a multiple "
+                        "of chunk size", dir->i_ino);
         goto fail;
 Eshort:
         error = "rec_len is smaller than minimal";
@@ -166,32 +166,36 @@ Espan:
 Einumber:
         error = "inode out of bounds";
 bad_entry:
-        ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - "
-                "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
-                dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
-                (unsigned long) le32_to_cpu(p->inode),
-                rec_len, p->name_len);
+        if (!quiet)
+                ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - "
+                        "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
+                        dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
+                        (unsigned long) le32_to_cpu(p->inode),
+                        rec_len, p->name_len);
         goto fail;
 Eend:
-        p = (ext2_dirent *)(kaddr + offs);
-        ext2_error (sb, "ext2_check_page",
-                "entry in directory #%lu spans the page boundary"
-                "offset=%lu, inode=%lu",
-                dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
-                (unsigned long) le32_to_cpu(p->inode));
+        if (!quiet) {
+                p = (ext2_dirent *)(kaddr + offs);
+                ext2_error(sb, "ext2_check_page",
+                        "entry in directory #%lu spans the page boundary"
+                        "offset=%lu, inode=%lu",
+                        dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
+                        (unsigned long) le32_to_cpu(p->inode));
+        }
 fail:
         SetPageChecked(page);
         SetPageError(page);
 }
 
-static struct page * ext2_get_page(struct inode *dir, unsigned long n)
+static struct page * ext2_get_page(struct inode *dir, unsigned long n,
+                                   int quiet)
 {
         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))
-                        ext2_check_page(page);
+                        ext2_check_page(page, quiet);
                 if (PageError(page))
                         goto fail;
         }
@@ -292,7 +296,7 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
         for ( ; n < npages; n++, offset = 0) {
                 char *kaddr, *limit;
                 ext2_dirent *de;
-                struct page *page = ext2_get_page(inode, n);
+                struct page *page = ext2_get_page(inode, n, 0);
 
                 if (IS_ERR(page)) {
                         ext2_error(sb, __func__,
@@ -361,6 +365,7 @@ struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
         struct page *page = NULL;
         struct ext2_inode_info *ei = EXT2_I(dir);
         ext2_dirent * de;
+        int dir_has_error = 0;
 
         if (npages == 0)
                 goto out;
@@ -374,7 +379,7 @@ struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
         n = start;
         do {
                 char *kaddr;
-                page = ext2_get_page(dir, n);
+                page = ext2_get_page(dir, n, dir_has_error);
                 if (!IS_ERR(page)) {
                         kaddr = page_address(page);
                         de = (ext2_dirent *) kaddr;
@@ -391,7 +396,9 @@ struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
                                 de = ext2_next_entry(de);
                         }
                         ext2_put_page(page);
-                }
+                } else
+                        dir_has_error = 1;
+
                 if (++n >= npages)
                         n = 0;
                 /* next page is past the blocks we've got */
@@ -414,7 +421,7 @@ found:
 
 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
 {
-        struct page *page = ext2_get_page(dir, 0);
+        struct page *page = ext2_get_page(dir, 0, 0);
         ext2_dirent *de = NULL;
 
         if (!IS_ERR(page)) {
@@ -487,7 +494,7 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
         for (n = 0; n <= npages; n++) {
                 char *dir_end;
 
-                page = ext2_get_page(dir, n);
+                page = ext2_get_page(dir, n, 0);
                 err = PTR_ERR(page);
                 if (IS_ERR(page))
                         goto out;
@@ -655,14 +662,17 @@ int ext2_empty_dir (struct inode * inode)
 {
         struct page *page = NULL;
         unsigned long i, npages = dir_pages(inode);
+        int dir_has_error = 0;
 
         for (i = 0; i < npages; i++) {
                 char *kaddr;
                 ext2_dirent * de;
-                page = ext2_get_page(inode, i);
+                page = ext2_get_page(inode, i, dir_has_error);
 
-                if (IS_ERR(page))
+                if (IS_ERR(page)) {
+                        dir_has_error = 1;
                         continue;
+                }
 
                 kaddr = page_address(page);
                 de = (ext2_dirent *)kaddr;