ext3/ext4: Factor out disk addressability check

As part of adding support for OCFS2 to mount huge volumes, we need to
check that the sector_t and page cache of the system are capable of
addressing the entire volume.

An identical check already appears in ext3 and ext4.  This patch moves
the addressability check into its own function in fs/libfs.c and
modifies ext3 and ext4 to invoke it.

[Edited to -EINVAL instead of BUG_ON() for bad blocksize_bits -- Joel]

Signed-off-by: Patrick LoPresti <lopresti@gmail.com>
Cc: linux-ext4@vger.kernel.org
Acked-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 5dbf4dba03c4d99240edd76de5e9a0a2bba4bd04..a367dd04428070cde6fbf7c70bbd64754ce498db 100644 (file)
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -1849,8 +1849,8 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
                goto failed_mount;
        }
 
-       if (le32_to_cpu(es->s_blocks_count) >
-                   (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
+       if (generic_check_addressable(sb->s_blocksize_bits,
+                                     le32_to_cpu(es->s_blocks_count))) {
                ext3_msg(sb, KERN_ERR,
                        "error: filesystem is too large to mount safely");
                if (sizeof(sector_t) < 8)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 26147746c272c2112b7067aa6415800434586b50..7f47c366bf1576fbbdf3cbe6441fc04afd9ca198 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2831,15 +2831,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
         * Test whether we have more sectors than will fit in sector_t,
         * and whether the max offset is addressable by the page cache.
         */
-       if ((ext4_blocks_count(es) >
-            (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) ||
-           (ext4_blocks_count(es) >
-            (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - sb->s_blocksize_bits))) {
+       ret = generic_check_addressable(sb->s_blocksize_bits,
+                                       ext4_blocks_count(es));
+       if (ret) {
                ext4_msg(sb, KERN_ERR, "filesystem"
                         " too large to mount safely on this system");
                if (sizeof(sector_t) < 8)
                        ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
-               ret = -EFBIG;
                goto failed_mount;
        }
 

diff --git a/fs/libfs.c b/fs/libfs.c
index 0a9da95317f76a6ffdebb9120a3e71dc0ff4cf72..8debe7b337697fbde663c1fb1b5e3eaed3cb5567 100644 (file)
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -913,6 +913,35 @@ int generic_file_fsync(struct file *file, int datasync)
 }
 EXPORT_SYMBOL(generic_file_fsync);
 
+/**
+ * generic_check_addressable - Check addressability of file system
+ * @blocksize_bits:    log of file system block size
+ * @num_blocks:                number of blocks in file system
+ *
+ * Determine whether a file system with @num_blocks blocks (and a
+ * block size of 2**@blocksize_bits) is addressable by the sector_t
+ * and page cache of the system.  Return 0 if so and -EFBIG otherwise.
+ */
+int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
+{
+       u64 last_fs_block = num_blocks - 1;
+
+       if (unlikely(num_blocks == 0))
+               return 0;
+
+       if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT))
+               return -EINVAL;
+
+       if ((last_fs_block >
+            (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
+           (last_fs_block >
+            (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - blocksize_bits))) {
+               return -EFBIG;
+       }
+       return 0;
+}
+EXPORT_SYMBOL(generic_check_addressable);
+
 /*
  * No-op implementation of ->fsync for in-memory filesystems.
  */

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 76041b6147582ef62eb0daedafbf1771a8e844c6..1a759f40ab9ed10cecaa113c0179be9ccb10529f 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2374,6 +2374,8 @@ extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
 
 extern int generic_file_fsync(struct file *, int);
 
+extern int generic_check_addressable(unsigned, u64);
+
 #ifdef CONFIG_MIGRATION
 extern int buffer_migrate_page(struct address_space *,
                                struct page *, struct page *);