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Subject[PATCH 13/49] ext4: different maxbytes functions for bitmap & extent files
Date
From: Eric Sandeen <sandeen@redhat.com>

use 2 different maxbytes functions for bitmapped & extent-based
files.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---
fs/ext4/super.c | 45 ++++++++++++++++++++++++++++++++++++++++++---
1 files changed, 42 insertions(+), 3 deletions(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 64067de..c79e46b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1600,19 +1600,58 @@ static void ext4_orphan_cleanup (struct super_block * sb,
#endif
sb->s_flags = s_flags; /* Restore MS_RDONLY status */
}
+/*
+ * 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 file size. There is a direct, and {,double-,triple-}indirect
+ * Maximal bitmap file size. There is a direct, and {,double-,triple-}indirect
* block limit, and also a limit of (2^48 - 1) 512-byte sectors in i_blocks.
* We need to be 1 filesystem block less than the 2^48 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 2^48 -1
* __u32 i_blocks_lo and _u16 i_blocks_high representing the
--
1.5.4.rc3.31.g1271-dirty


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