summaryrefslogtreecommitdiff
path: root/Documentation/filesystems
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/btrfs.txt16
-rw-r--r--Documentation/filesystems/debugfs.txt40
-rw-r--r--Documentation/filesystems/sysfs.txt5
3 files changed, 52 insertions, 9 deletions
diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt
index d11cc2f8077b..c772b47e7ef0 100644
--- a/Documentation/filesystems/btrfs.txt
+++ b/Documentation/filesystems/btrfs.txt
@@ -61,7 +61,7 @@ Options with (*) are default options and will not show in the mount options.
check_int enables the integrity checker module, which examines all
block write requests to ensure on-disk consistency, at a large
- memory and CPU cost.
+ memory and CPU cost.
check_int_data includes extent data in the integrity checks, and
implies the check_int option.
@@ -113,7 +113,7 @@ Options with (*) are default options and will not show in the mount options.
Disable/enable debugging option to be more verbose in some ENOSPC conditions.
fatal_errors=<action>
- Action to take when encountering a fatal error:
+ Action to take when encountering a fatal error:
"bug" - BUG() on a fatal error. This is the default.
"panic" - panic() on a fatal error.
@@ -132,10 +132,10 @@ Options with (*) are default options and will not show in the mount options.
max_inline=<bytes>
Specify the maximum amount of space, in bytes, that can be inlined in
- a metadata B-tree leaf. The value is specified in bytes, optionally
+ a metadata B-tree leaf. The value is specified in bytes, optionally
with a K, M, or G suffix, case insensitive. In practice, this value
is limited by the root sector size, with some space unavailable due
- to leaf headers. For a 4k sectorsize, max inline data is ~3900 bytes.
+ to leaf headers. For a 4k sector size, max inline data is ~3900 bytes.
metadata_ratio=<value>
Specify that 1 metadata chunk should be allocated after every <value>
@@ -170,7 +170,7 @@ Options with (*) are default options and will not show in the mount options.
recovery
Enable autorecovery attempts if a bad tree root is found at mount time.
- Currently this scans a list of several previous tree roots and tries to
+ Currently this scans a list of several previous tree roots and tries to
use the first readable.
rescan_uuid_tree
@@ -194,7 +194,7 @@ Options with (*) are default options and will not show in the mount options.
ssd_spread
Options to control ssd allocation schemes. By default, BTRFS will
enable or disable ssd allocation heuristics depending on whether a
- rotational or nonrotational disk is in use. The ssd and nossd options
+ rotational or non-rotational disk is in use. The ssd and nossd options
can override this autodetection.
The ssd_spread mount option attempts to allocate into big chunks
@@ -216,13 +216,13 @@ Options with (*) are default options and will not show in the mount options.
This allows mounting of subvolumes which are not in the root of the mounted
filesystem.
You can use "btrfs subvolume show " to see the object ID for a subvolume.
-
+
thread_pool=<number>
The number of worker threads to allocate. The default number is equal
to the number of CPUs + 2, or 8, whichever is smaller.
user_subvol_rm_allowed
- Allow subvolumes to be deleted by a non-root user. Use with caution.
+ Allow subvolumes to be deleted by a non-root user. Use with caution.
MAILING LIST
============
diff --git a/Documentation/filesystems/debugfs.txt b/Documentation/filesystems/debugfs.txt
index 88ab81c79109..463f595733e8 100644
--- a/Documentation/filesystems/debugfs.txt
+++ b/Documentation/filesystems/debugfs.txt
@@ -51,6 +51,17 @@ operations should be provided; others can be included as needed. Again,
the return value will be a dentry pointer to the created file, NULL for
error, or ERR_PTR(-ENODEV) if debugfs support is missing.
+Create a file with an initial size, the following function can be used
+instead:
+
+ struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
+ struct dentry *parent, void *data,
+ const struct file_operations *fops,
+ loff_t file_size);
+
+file_size is the initial file size. The other parameters are the same
+as the function debugfs_create_file.
+
In a number of cases, the creation of a set of file operations is not
actually necessary; the debugfs code provides a number of helper functions
for simple situations. Files containing a single integer value can be
@@ -100,6 +111,14 @@ A read on the resulting file will yield either Y (for non-zero values) or
N, followed by a newline. If written to, it will accept either upper- or
lower-case values, or 1 or 0. Any other input will be silently ignored.
+Also, atomic_t values can be placed in debugfs with:
+
+ struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
+ struct dentry *parent, atomic_t *value)
+
+A read of this file will get atomic_t values, and a write of this file
+will set atomic_t values.
+
Another option is exporting a block of arbitrary binary data, with
this structure and function:
@@ -147,6 +166,27 @@ The "base" argument may be 0, but you may want to build the reg32 array
using __stringify, and a number of register names (macros) are actually
byte offsets over a base for the register block.
+If you want to dump an u32 array in debugfs, you can create file with:
+
+ struct dentry *debugfs_create_u32_array(const char *name, umode_t mode,
+ struct dentry *parent,
+ u32 *array, u32 elements);
+
+The "array" argument provides data, and the "elements" argument is
+the number of elements in the array. Note: Once array is created its
+size can not be changed.
+
+There is a helper function to create device related seq_file:
+
+ struct dentry *debugfs_create_devm_seqfile(struct device *dev,
+ const char *name,
+ struct dentry *parent,
+ int (*read_fn)(struct seq_file *s,
+ void *data));
+
+The "dev" argument is the device related to this debugfs file, and
+the "read_fn" is a function pointer which to be called to print the
+seq_file content.
There are a couple of other directory-oriented helper functions:
diff --git a/Documentation/filesystems/sysfs.txt b/Documentation/filesystems/sysfs.txt
index b35a64b82f9e..9494afb9476a 100644
--- a/Documentation/filesystems/sysfs.txt
+++ b/Documentation/filesystems/sysfs.txt
@@ -212,7 +212,10 @@ Other notes:
- show() methods should return the number of bytes printed into the
buffer. This is the return value of scnprintf().
-- show() should always use scnprintf().
+- show() must not use snprintf() when formatting the value to be
+ returned to user space. If you can guarantee that an overflow
+ will never happen you can use sprintf() otherwise you must use
+ scnprintf().
- store() should return the number of bytes used from the buffer. If the
entire buffer has been used, just return the count argument.