Basic approach: have both ext4_max_bitmap_size() and ext4_max_size()
functions to compute max offsets for both types of formats.
Use vfs sb->s_maxbytes for the "native" maxbytes, i.e. extent-format files.
Put the smaller bitmap limit in a new sbi->s_bitmap_maxbytes in the ext4
superblock info structure.
Catch bitmap files in ext4_file_write() and ext4_setattr() to limit
extending writes, llseeks, and truncates to too-large offsets which the
VFS let through due to the extent-format maxbytes. On write, allow
writes up to the max, but then stop, by using iov_shorten() to limit the
size of the write to the maximum.
3 patches follow:
ext4_two_maxbytes_functions.patch - differentiate the maxbytes f'ns
ext4_bitmap_maxbytes_vfs.patch - export iov_shorten from kernel
ext4_bitmap_maxbytes.patch - store, and limit to, bitmap_maxbytes
Comments?
Thanks,
-Eric
use 2 different maxbytes functions for bitmapped & extent-based
files.
Signed-off-by: Eric Sandeen <[email protected]>
---
Index: linux-2.6.24-rc3/fs/ext4/super.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/ext4/super.c
+++ linux-2.6.24-rc3/fs/ext4/super.c
@@ -1656,17 +1656,57 @@ static void ext4_orphan_cleanup (struct
}
/*
- * Maximal file size. There is a direct, and {,double-,triple-}indirect
+ * Maximal extent format file size.
+ * Resulting logical blkno at s_maxbytes must fit in our on-disk
+ * extent format containers, within a sector_t, and within i_blocks
+ * in the vfs. ext4 inode has 48 bits of i_block in fsblock units,
+ * so that won't be a limiting factor.
+ *
+ * Note, this does *not* consider any metadata overhead for vfs i_blocks.
+ */
+static loff_t ext4_max_size(int blkbits)
+{
+ loff_t res;
+ loff_t upper_limit = MAX_LFS_FILESIZE;
+
+ /* small i_blocks in vfs inode? */
+ if (sizeof(blkcnt_t) < sizeof(u64)) {
+ /*
+ * CONFIG_LSF is not enabled implies the inode
+ * i_block represent total blocks in 512 bytes
+ * 32 == size of vfs inode i_blocks * 8
+ */
+ upper_limit = (1LL << 32) - 1;
+
+ /* total blocks in file system block size */
+ upper_limit >>= (blkbits - 9);
+ upper_limit <<= blkbits;
+ }
+
+ /* 32-bit extent-start container, ee_block */
+ res = 1LL << 32;
+ res <<= blkbits;
+ res -= 1;
+
+ /* Sanity check against vm- & vfs- imposed limits */
+ if (res > upper_limit)
+ res = upper_limit;
+
+ return res;
+}
+
+/*
+ * Maximal bitmap file size. There is a direct, and {,double-,triple-}indirect
* block limit, and also a limit of (248 - 1) 512-byte sectors in i_blocks.
* We need to be 1 filesystem block less than the 248 sector limit.
*/
-static loff_t ext4_max_size(int bits)
+static loff_t ext4_max_bitmap_size(int bits)
{
loff_t res = EXT4_NDIR_BLOCKS;
int meta_blocks;
loff_t upper_limit;
/* This is calculated to be the largest file size for a
- * dense, file such that the total number of
+ * dense, bitmapped file such that the total number of
* sectors in the file, including data and all indirect blocks,
* does not exceed 248 -1
* __u32 i_blocks_lo and _u16 i_blocks_high representing the
Export iov_shorten() from kernel so that ext4 can
truncate too-large writes to bitmapped files.
Signed-off-by: Eric Sandeen <[email protected]>
---
Index: linux-2.6.24-rc3/fs/read_write.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/read_write.c
+++ linux-2.6.24-rc3/fs/read_write.c
@@ -451,6 +451,8 @@ unsigned long iov_shorten(struct iovec *
return seg;
}
+EXPORT_SYMBOL(iov_shorten);
+
ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov,
unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn)
{
Calculate & store the max offset for bitmapped files, and
catch too-large seeks, truncates, and writes in ext4, shortening
or rejecting as appropriate.
Signed-off-by: Eric Sandeen <[email protected]>
---
Index: linux-2.6.24-rc3/fs/ext4/super.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/ext4/super.c
+++ linux-2.6.24-rc3/fs/ext4/super.c
@@ -1979,6 +1979,7 @@ static int ext4_fill_super (struct super
}
}
+ sbi->s_bitmap_maxbytes = ext4_max_bitmap_size(sb->s_blocksize_bits);
sb->s_maxbytes = ext4_max_size(sb->s_blocksize_bits);
if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {
Index: linux-2.6.24-rc3/fs/ext4/file.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/ext4/file.c
+++ linux-2.6.24-rc3/fs/ext4/file.c
@@ -56,8 +56,25 @@ ext4_file_write(struct kiocb *iocb, cons
ssize_t ret;
int err;
- ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
+ /*
+ * If we have encountered a bitmap-format file, the size limit
+ * is smaller than s_maxbytes, which is for extent-mapped files.
+ */
+ if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ size_t length = iov_length(iov, nr_segs);
+
+ if (pos > sbi->s_bitmap_maxbytes)
+ return -EFBIG;
+
+ if (pos + length > sbi->s_bitmap_maxbytes) {
+ nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
+ sbi->s_bitmap_maxbytes - pos);
+ }
+ }
+
+ ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
/*
* Skip flushing if there was an error, or if nothing was written.
*/
Index: linux-2.6.24-rc3/fs/ext4/inode.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/ext4/inode.c
+++ linux-2.6.24-rc3/fs/ext4/inode.c
@@ -309,7 +309,9 @@ static int ext4_block_to_path(struct ino
offsets[n++] = i_block & (ptrs - 1);
final = ptrs;
} else {
- ext4_warning(inode->i_sb, "ext4_block_to_path", "block > big");
+ ext4_warning(inode->i_sb, "ext4_block_to_path", "block %u > max",
+ i_block + direct_blocks +
+ indirect_blocks + double_blocks);
}
if (boundary)
*boundary = final - 1 - (i_block & (ptrs - 1));
@@ -3212,6 +3214,17 @@ int ext4_setattr(struct dentry *dentry,
ext4_journal_stop(handle);
}
+ if (attr->ia_valid & ATTR_SIZE) {
+ if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+ if (attr->ia_size > sbi->s_bitmap_maxbytes) {
+ error = -EFBIG;
+ goto err_out;
+ }
+ }
+ }
+
if (S_ISREG(inode->i_mode) &&
attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
handle_t *handle;
Index: linux-2.6.24-rc3/include/linux/ext4_fs_sb.h
===================================================================
--- linux-2.6.24-rc3.orig/include/linux/ext4_fs_sb.h
+++ linux-2.6.24-rc3/include/linux/ext4_fs_sb.h
@@ -38,6 +38,7 @@ struct ext4_sb_info {
ext4_group_t s_groups_count; /* Number of groups in the fs */
unsigned long s_overhead_last; /* Last calculated overhead */
unsigned long s_blocks_last; /* Last seen block count */
+ loff_t s_bitmap_maxbytes; /* max bytes for bitmap files */
struct buffer_head * s_sbh; /* Buffer containing the super block */
struct ext4_super_block * s_es; /* Pointer to the super block in the buffer */
struct buffer_head ** s_group_desc;
Crud, minor off-by-one in ext4_file_write. V2 below:
===============================
Calculate & store the max offset for bitmapped files, and
catch too-large seeks, truncates, and writes in ext4, shortening
or rejecting as appropriate.
Signed-off-by: Eric Sandeen <[email protected]>
---
Index: linux-2.6.24-rc3/fs/ext4/super.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/ext4/super.c
+++ linux-2.6.24-rc3/fs/ext4/super.c
@@ -1979,6 +1979,7 @@ static int ext4_fill_super (struct super
}
}
+ sbi->s_bitmap_maxbytes = ext4_max_bitmap_size(sb->s_blocksize_bits);
sb->s_maxbytes = ext4_max_size(sb->s_blocksize_bits);
if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {
Index: linux-2.6.24-rc3/fs/ext4/file.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/ext4/file.c
+++ linux-2.6.24-rc3/fs/ext4/file.c
@@ -56,8 +56,29 @@ ext4_file_write(struct kiocb *iocb, cons
ssize_t ret;
int err;
- ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
+ /*
+ * If we have encountered a bitmap-format file, the size limit
+ * is smaller than s_maxbytes, which is for extent-mapped files.
+ */
+ if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ size_t length = iov_length(iov, nr_segs);
+
+ if (pos >= sbi->s_bitmap_maxbytes) {
+ if (length || pos > sbi->s_bitmap_maxbytes) {
+ return -EFBIG;
+ }
+ /* zero-length writes at maxbytes are OK */
+ }
+
+ if (pos + length > sbi->s_bitmap_maxbytes) {
+ nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
+ sbi->s_bitmap_maxbytes - pos);
+ }
+ }
+
+ ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
/*
* Skip flushing if there was an error, or if nothing was written.
*/
Index: linux-2.6.24-rc3/fs/ext4/inode.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/ext4/inode.c
+++ linux-2.6.24-rc3/fs/ext4/inode.c
@@ -309,7 +309,9 @@ static int ext4_block_to_path(struct ino
offsets[n++] = i_block & (ptrs - 1);
final = ptrs;
} else {
- ext4_warning(inode->i_sb, "ext4_block_to_path", "block > big");
+ ext4_warning(inode->i_sb, "ext4_block_to_path", "block %u > max",
+ i_block + direct_blocks +
+ indirect_blocks + double_blocks);
}
if (boundary)
*boundary = final - 1 - (i_block & (ptrs - 1));
@@ -3212,6 +3214,17 @@ int ext4_setattr(struct dentry *dentry,
ext4_journal_stop(handle);
}
+ if (attr->ia_valid & ATTR_SIZE) {
+ if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+ if (attr->ia_size > sbi->s_bitmap_maxbytes) {
+ error = -EFBIG;
+ goto err_out;
+ }
+ }
+ }
+
if (S_ISREG(inode->i_mode) &&
attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
handle_t *handle;
Index: linux-2.6.24-rc3/include/linux/ext4_fs_sb.h
===================================================================
--- linux-2.6.24-rc3.orig/include/linux/ext4_fs_sb.h
+++ linux-2.6.24-rc3/include/linux/ext4_fs_sb.h
@@ -38,6 +38,7 @@ struct ext4_sb_info {
ext4_group_t s_groups_count; /* Number of groups in the fs */
unsigned long s_overhead_last; /* Last calculated overhead */
unsigned long s_blocks_last; /* Last seen block count */
+ loff_t s_bitmap_maxbytes; /* max bytes for bitmap files */
struct buffer_head * s_sbh; /* Buffer containing the super block */
struct ext4_super_block * s_es; /* Pointer to the super block in the buffer */
struct buffer_head ** s_group_desc;
On Dec 04, 2007 09:58 -0600, Eric Sandeen wrote:
> +static loff_t ext4_max_size(int blkbits)
> +{
> + loff_t res;
> + loff_t upper_limit = MAX_LFS_FILESIZE;
> +
> + /* small i_blocks in vfs inode? */
> + if (sizeof(blkcnt_t) < sizeof(u64)) {
It would probably be more future-proof by having a struct inode here and
using "if (sizeof(inode->i_blocks) < sizeof(__u64))".
> + upper_limit = (1LL << 32) - 1;
> +
> + /* total blocks in file system block size */
> + upper_limit >>= (blkbits - 9);
> + upper_limit <<= blkbits;
There is probably a cleaner way to do this, maybe:
upper_limit = (1LL << (32 + 9) - 1) & ~((1 << blkbits) - 1);
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
Andreas Dilger wrote:
> On Dec 04, 2007 09:58 -0600, Eric Sandeen wrote:
>> +static loff_t ext4_max_size(int blkbits)
>> +{
>> + loff_t res;
>> + loff_t upper_limit = MAX_LFS_FILESIZE;
>> +
>> + /* small i_blocks in vfs inode? */
>> + if (sizeof(blkcnt_t) < sizeof(u64)) {
>
> It would probably be more future-proof by having a struct inode here and
> using "if (sizeof(inode->i_blocks) < sizeof(__u64))".
Ok. Honestly these were both just lifted from the original max_size
function for bitmap files :)
-Eric
>> + upper_limit = (1LL << 32) - 1;
>> +
>> + /* total blocks in file system block size */
>> + upper_limit >>= (blkbits - 9);
>> + upper_limit <<= blkbits;
>
> There is probably a cleaner way to do this, maybe:
> upper_limit = (1LL << (32 + 9) - 1) & ~((1 << blkbits) - 1);
>
> Cheers, Andreas
> --
> Andreas Dilger
> Sr. Staff Engineer, Lustre Group
> Sun Microsystems of Canada, Inc.
>