Convert s_r_blocks_count and s_free_blocks_count to s_r_blocks_count_lo and s_free_blocks_count_lo This helps in finding BUGs due to direct partial access of these split 64 bit values Also fix direct partial access in ext4 code Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Convert s_blocks_count to s_blocks_count_lo This helps in finding BUGs due to direct partial access of these split 64 bit values Also fix direct partial access in ext4 code Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Convert bg_inode_bitmap and bg_inode_table to bg_inode_bitmap_lo and bg_inode_table_lo. This helps in finding BUGs due to direct partial access of these split 64 bit values Also fix one direct partial access Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Convert bg_block_bitmap to bg_block_bitmap_lo This helps in catching some BUGS due to direct partial access of these split fields. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
This feature relaxes check restrictions on where each block groups meta data is located within the storage media. This allows for the allocation of bitmaps or inode tables outside the block group boundaries in cases where bad blocks forces us to look for new blocks which the owning block group can not satisfy. This will also allow for new meta-data allocation schemes to improve performance and scalability. Signed-off-by: Jose R. Santos <jrs@us.ibm.com> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In pass1 of e2fsck, every inode table in the fileystem is scanned and checked,
regardless of whether it is in use. This is this the most time consuming part
of the filesystem check. The unintialized block group feature can greatly
reduce e2fsck time by eliminating checking of uninitialized inodes.
With this feature, there is a a high water mark of used inodes for each block
group. Block and inode bitmaps can be uninitialized on disk via a flag in the
group descriptor to avoid reading or scanning them at e2fsck time. A checksum
of each group descriptor is used to ensure that corruption in the group
descriptor's bit flags does not cause incorrect operation.
The feature is enabled through a mkfs option
mke2fs /dev/ -O uninit_groups
A patch adding support for uninitialized block groups to e2fsprogs tools has
been posted to the linux-ext4 mailing list.
The patches have been stress tested with fsstress and fsx. In performance
tests testing e2fsck time, we have seen that e2fsck time on ext3 grows
linearly with the total number of inodes in the filesytem. In ext4 with the
uninitialized block groups feature, the e2fsck time is constant, based
solely on the number of used inodes rather than the total inode count.
Since typical ext4 filesystems only use 1-10% of their inodes, this feature can
greatly reduce e2fsck time for users. With performance improvement of 2-20
times, depending on how full the filesystem is.
The attached graph shows the major improvements in e2fsck times in filesystems
with a large total inode count, but few inodes in use.
In each group descriptor if we have
EXT4_BG_INODE_UNINIT set in bg_flags:
Inode table is not initialized/used in this group. So we can skip
the consistency check during fsck.
EXT4_BG_BLOCK_UNINIT set in bg_flags:
No block in the group is used. So we can skip the block bitmap
verification for this group.
We also add two new fields to group descriptor as a part of
uninitialized group patch.
__le16 bg_itable_unused; /* Unused inodes count */
__le16 bg_checksum; /* crc16(sb_uuid+group+desc) */
bg_itable_unused:
If we have EXT4_BG_INODE_UNINIT not set in bg_flags
then bg_itable_unused will give the offset within
the inode table till the inodes are used. This can be
used by fsck to skip list of inodes that are marked unused.
bg_checksum:
Now that we depend on bg_flags and bg_itable_unused to determine
the block and inode usage, we need to make sure group descriptor
is not corrupt. We add checksum to group descriptor to
detect corruption. If the descriptor is found to be corrupt, we
mark all the blocks and inodes in the group used.
Signed-off-by: Avantika Mathur <mathur@us.ibm.com>
Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
CONFIG_EXT4_INDEX is not an exposed config option in the kernel, and it is unconditionally defined in ext4_fs.h. tune2fs is already able to turn off dir indexing, so at this point it's just cluttering up the code. Remove it. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Mingming Cao <cmm@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Fragment support in ext2/3/4 was never implemented, and it probably will never be implemented. So remove it from ext4. Signed-off-by: Coly Li <coyli@suse.de> Acked-by: Andreas Dilger <adilger@clusterfs.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This patch adds support to ext4 for allowing more than 65000 subdirectories. Currently the maximum number of subdirectories is capped at 32000. If we exceed 65000 subdirectories in an htree directory it sets the inode link count to 1 and no longer counts subdirectories. The directory link count is not actually used when determining if a directory is empty, as that only counts subdirectories and not regular files that might be in there. A EXT4_FEATURE_RO_COMPAT_DIR_NLINK flag has been added and it is set if the subdir count for any directory crosses 65000. A later fsck will clear EXT4_FEATURE_RO_COMPAT_DIR_NLINK if there are no longer any directory with >65000 subdirs. Signed-off-by: Andreas Dilger <adilger@clusterfs.com> Signed-off-by: Kalpak Shah <kalpak@clusterfs.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>