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-rw-r--r--Documentation/filesystems/ext4.txt25
1 files changed, 21 insertions, 4 deletions
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 80e193d82e2e..eb154ef36c2a 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -26,9 +26,15 @@ Mailing list: linux-ext4@vger.kernel.org
git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git
- - Create a new filesystem using the ext4dev filesystem type:
+ - Note that it is highly important to install the mke2fs.conf file
+ that comes with the e2fsprogs 1.41.x sources in /etc/mke2fs.conf. If
+ you have edited the /etc/mke2fs.conf file installed on your system,
+ you will need to merge your changes with the version from e2fsprogs
+ 1.41.x.
- # mke2fs -t ext4dev /dev/hda1
+ - Create a new filesystem using the ext4 filesystem type:
+
+ # mke2fs -t ext4 /dev/hda1
Or configure an existing ext3 filesystem to support extents and set
the test_fs flag to indicate that it's ok for an in-development
@@ -41,13 +47,13 @@ Mailing list: linux-ext4@vger.kernel.org
# tune2fs -I 256 /dev/hda1
- (Note: we currently do not have tools to convert an ext4dev
+ (Note: we currently do not have tools to convert an ext4
filesystem back to ext3; so please do not do try this on production
filesystems.)
- Mounting:
- # mount -t ext4dev /dev/hda1 /wherever
+ # mount -t ext4 /dev/hda1 /wherever
- When comparing performance with other filesystems, remember that
ext3/4 by default offers higher data integrity guarantees than most.
@@ -171,6 +177,11 @@ barrier=<0|1(*)> This enables/disables the use of write barriers in
your disks are battery-backed in one way or another,
disabling barriers may safely improve performance.
+inode_readahead=n This tuning parameter controls the maximum
+ number of inode table blocks that ext4's inode
+ table readahead algorithm will pre-read into
+ the buffer cache. The default value is 32 blocks.
+
orlov (*) This enables the new Orlov block allocator. It is
enabled by default.
@@ -212,6 +223,11 @@ errors=remount-ro(*) Remount the filesystem read-only on an error.
errors=continue Keep going on a filesystem error.
errors=panic Panic and halt the machine if an error occurs.
+data_err=ignore(*) Just print an error message if an error occurs
+ in a file data buffer in ordered mode.
+data_err=abort Abort the journal if an error occurs in a file
+ data buffer in ordered mode.
+
grpid Give objects the same group ID as their creator.
bsdgroups
@@ -246,6 +262,7 @@ stripe=n Number of filesystem blocks that mballoc will try
delalloc (*) Deferring block allocation until write-out time.
nodelalloc Disable delayed allocation. Blocks are allocation
when data is copied from user to page cache.
+
Data Mode
=========
There are 3 different data modes: