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authorLinus Torvalds <torvalds@linux-foundation.org>2018-10-24 12:42:24 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2018-10-24 12:42:24 -0400
commit5993692f09582accb4cb7af11d344598af43c3b8 (patch)
tree062447eb44769d6da6e50302853eac1bb1d6e5d3 /Documentation/filesystems
parentd6edff78fe9e34dbea1bec7dc26cfce92c6d96d5 (diff)
parent33458eaba4dfe778a426df6a19b7aad2ff9f7eec (diff)
Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o: - further restructure ext4 documentation - fix up ext4's delayed allocation for bigalloc file systems - fix up some syzbot-detected races in EXT4_IOC_MOVE_EXT, EXT4_IOC_SWAP_BOOT, and ext4_remount - ... and a few other miscellaneous bugs and optimizations. * tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (21 commits) ext4: fix use-after-free race in ext4_remount()'s error path ext4: cache NULL when both default_acl and acl are NULL docs: promote the ext4 data structures book to top level docs: move ext4 administrative docs to admin-guide/ jbd2: fix use after free in jbd2_log_do_checkpoint() ext4: propagate error from dquot_initialize() in EXT4_IOC_FSSETXATTR ext4: fix setattr project check in fssetxattr ioctl docs: make ext4 readme tables readable docs: fix ext4 documentation table formatting problems docs: generate a separate ext4 pdf file from the documentation ext4: convert fault handler to use vm_fault_t type ext4: initialize retries variable in ext4_da_write_inline_data_begin() ext4: fix EXT4_IOC_SWAP_BOOT ext4: fix build error when DX_DEBUG is defined ext4: fix argument checking in EXT4_IOC_MOVE_EXT ext4: fix reserved cluster accounting at page invalidation time ext4: adjust reserved cluster count when removing extents ext4: reduce reserved cluster count by number of allocated clusters ext4: fix reserved cluster accounting at delayed write time ext4: add new pending reservation mechanism ...
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/ext4/about.rst (renamed from Documentation/filesystems/ext4/ondisk/about.rst)0
-rw-r--r--Documentation/filesystems/ext4/allocators.rst (renamed from Documentation/filesystems/ext4/ondisk/allocators.rst)0
-rw-r--r--Documentation/filesystems/ext4/attributes.rst (renamed from Documentation/filesystems/ext4/ondisk/attributes.rst)8
-rw-r--r--Documentation/filesystems/ext4/bigalloc.rst (renamed from Documentation/filesystems/ext4/ondisk/bigalloc.rst)0
-rw-r--r--Documentation/filesystems/ext4/bitmaps.rst (renamed from Documentation/filesystems/ext4/ondisk/bitmaps.rst)0
-rw-r--r--Documentation/filesystems/ext4/blockgroup.rst (renamed from Documentation/filesystems/ext4/ondisk/blockgroup.rst)0
-rw-r--r--Documentation/filesystems/ext4/blockmap.rst (renamed from Documentation/filesystems/ext4/ondisk/blockmap.rst)0
-rw-r--r--Documentation/filesystems/ext4/blocks.rst (renamed from Documentation/filesystems/ext4/ondisk/blocks.rst)0
-rw-r--r--Documentation/filesystems/ext4/checksums.rst (renamed from Documentation/filesystems/ext4/ondisk/checksums.rst)2
-rw-r--r--Documentation/filesystems/ext4/directory.rst (renamed from Documentation/filesystems/ext4/ondisk/directory.rst)18
-rw-r--r--Documentation/filesystems/ext4/dynamic.rst (renamed from Documentation/filesystems/ext4/ondisk/dynamic.rst)0
-rw-r--r--Documentation/filesystems/ext4/eainode.rst (renamed from Documentation/filesystems/ext4/ondisk/eainode.rst)0
-rw-r--r--Documentation/filesystems/ext4/ext4.rst613
-rw-r--r--Documentation/filesystems/ext4/globals.rst (renamed from Documentation/filesystems/ext4/ondisk/globals.rst)0
-rw-r--r--Documentation/filesystems/ext4/group_descr.rst (renamed from Documentation/filesystems/ext4/ondisk/group_descr.rst)4
-rw-r--r--Documentation/filesystems/ext4/ifork.rst (renamed from Documentation/filesystems/ext4/ondisk/ifork.rst)8
-rw-r--r--Documentation/filesystems/ext4/index.rst19
-rw-r--r--Documentation/filesystems/ext4/inlinedata.rst (renamed from Documentation/filesystems/ext4/ondisk/inlinedata.rst)0
-rw-r--r--Documentation/filesystems/ext4/inodes.rst (renamed from Documentation/filesystems/ext4/ondisk/inodes.rst)19
-rw-r--r--Documentation/filesystems/ext4/journal.rst (renamed from Documentation/filesystems/ext4/ondisk/journal.rst)32
-rw-r--r--Documentation/filesystems/ext4/mmp.rst (renamed from Documentation/filesystems/ext4/ondisk/mmp.rst)2
-rw-r--r--Documentation/filesystems/ext4/ondisk/index.rst9
-rw-r--r--Documentation/filesystems/ext4/overview.rst (renamed from Documentation/filesystems/ext4/ondisk/overview.rst)0
-rw-r--r--Documentation/filesystems/ext4/special_inodes.rst (renamed from Documentation/filesystems/ext4/ondisk/special_inodes.rst)2
-rw-r--r--Documentation/filesystems/ext4/super.rst (renamed from Documentation/filesystems/ext4/ondisk/super.rst)24
25 files changed, 68 insertions, 692 deletions
diff --git a/Documentation/filesystems/ext4/ondisk/about.rst b/Documentation/filesystems/ext4/about.rst
index 0aadba052264..0aadba052264 100644
--- a/Documentation/filesystems/ext4/ondisk/about.rst
+++ b/Documentation/filesystems/ext4/about.rst
diff --git a/Documentation/filesystems/ext4/ondisk/allocators.rst b/Documentation/filesystems/ext4/allocators.rst
index 7aa85152ace3..7aa85152ace3 100644
--- a/Documentation/filesystems/ext4/ondisk/allocators.rst
+++ b/Documentation/filesystems/ext4/allocators.rst
diff --git a/Documentation/filesystems/ext4/ondisk/attributes.rst b/Documentation/filesystems/ext4/attributes.rst
index 0b01b67b81fe..54386a010a8d 100644
--- a/Documentation/filesystems/ext4/ondisk/attributes.rst
+++ b/Documentation/filesystems/ext4/attributes.rst
@@ -30,7 +30,7 @@ Extended attributes, when stored after the inode, have a header
30``ext4_xattr_ibody_header`` that is 4 bytes long: 30``ext4_xattr_ibody_header`` that is 4 bytes long:
31 31
32.. list-table:: 32.. list-table::
33 :widths: 1 1 1 77 33 :widths: 8 8 24 40
34 :header-rows: 1 34 :header-rows: 1
35 35
36 * - Offset 36 * - Offset
@@ -47,7 +47,7 @@ The beginning of an extended attribute block is in
47``struct ext4_xattr_header``, which is 32 bytes long: 47``struct ext4_xattr_header``, which is 32 bytes long:
48 48
49.. list-table:: 49.. list-table::
50 :widths: 1 1 1 77 50 :widths: 8 8 24 40
51 :header-rows: 1 51 :header-rows: 1
52 52
53 * - Offset 53 * - Offset
@@ -92,7 +92,7 @@ entries must be stored in sorted order. The sort order is
92Attributes stored inside an inode do not need be stored in sorted order. 92Attributes stored inside an inode do not need be stored in sorted order.
93 93
94.. list-table:: 94.. list-table::
95 :widths: 1 1 1 77 95 :widths: 8 8 24 40
96 :header-rows: 1 96 :header-rows: 1
97 97
98 * - Offset 98 * - Offset
@@ -157,7 +157,7 @@ attribute name index field is set, and matching string is removed from
157the key name. Here is a map of name index values to key prefixes: 157the key name. Here is a map of name index values to key prefixes:
158 158
159.. list-table:: 159.. list-table::
160 :widths: 1 79 160 :widths: 16 64
161 :header-rows: 1 161 :header-rows: 1
162 162
163 * - Name Index 163 * - Name Index
diff --git a/Documentation/filesystems/ext4/ondisk/bigalloc.rst b/Documentation/filesystems/ext4/bigalloc.rst
index c6d88557553c..c6d88557553c 100644
--- a/Documentation/filesystems/ext4/ondisk/bigalloc.rst
+++ b/Documentation/filesystems/ext4/bigalloc.rst
diff --git a/Documentation/filesystems/ext4/ondisk/bitmaps.rst b/Documentation/filesystems/ext4/bitmaps.rst
index c7546dbc197a..c7546dbc197a 100644
--- a/Documentation/filesystems/ext4/ondisk/bitmaps.rst
+++ b/Documentation/filesystems/ext4/bitmaps.rst
diff --git a/Documentation/filesystems/ext4/ondisk/blockgroup.rst b/Documentation/filesystems/ext4/blockgroup.rst
index baf888e4c06a..baf888e4c06a 100644
--- a/Documentation/filesystems/ext4/ondisk/blockgroup.rst
+++ b/Documentation/filesystems/ext4/blockgroup.rst
diff --git a/Documentation/filesystems/ext4/ondisk/blockmap.rst b/Documentation/filesystems/ext4/blockmap.rst
index 30e25750d88a..30e25750d88a 100644
--- a/Documentation/filesystems/ext4/ondisk/blockmap.rst
+++ b/Documentation/filesystems/ext4/blockmap.rst
diff --git a/Documentation/filesystems/ext4/ondisk/blocks.rst b/Documentation/filesystems/ext4/blocks.rst
index 73d4dc0f7bda..73d4dc0f7bda 100644
--- a/Documentation/filesystems/ext4/ondisk/blocks.rst
+++ b/Documentation/filesystems/ext4/blocks.rst
diff --git a/Documentation/filesystems/ext4/ondisk/checksums.rst b/Documentation/filesystems/ext4/checksums.rst
index 9d6a793b2e03..5519e253810d 100644
--- a/Documentation/filesystems/ext4/ondisk/checksums.rst
+++ b/Documentation/filesystems/ext4/checksums.rst
@@ -28,7 +28,7 @@ of checksum. The checksum function is whatever the superblock describes
28(crc32c as of October 2013) unless noted otherwise. 28(crc32c as of October 2013) unless noted otherwise.
29 29
30.. list-table:: 30.. list-table::
31 :widths: 1 1 4 31 :widths: 20 8 50
32 :header-rows: 1 32 :header-rows: 1
33 33
34 * - Metadata 34 * - Metadata
diff --git a/Documentation/filesystems/ext4/ondisk/directory.rst b/Documentation/filesystems/ext4/directory.rst
index 8fcba68c2884..614034e24669 100644
--- a/Documentation/filesystems/ext4/ondisk/directory.rst
+++ b/Documentation/filesystems/ext4/directory.rst
@@ -34,7 +34,7 @@ is at most 263 bytes long, though on disk you'll need to reference
34``dirent.rec_len`` to know for sure. 34``dirent.rec_len`` to know for sure.
35 35
36.. list-table:: 36.. list-table::
37 :widths: 1 1 1 77 37 :widths: 8 8 24 40
38 :header-rows: 1 38 :header-rows: 1
39 39
40 * - Offset 40 * - Offset
@@ -66,7 +66,7 @@ tree traversal. This format is ``ext4_dir_entry_2``, which is at most
66``dirent.rec_len`` to know for sure. 66``dirent.rec_len`` to know for sure.
67 67
68.. list-table:: 68.. list-table::
69 :widths: 1 1 1 77 69 :widths: 8 8 24 40
70 :header-rows: 1 70 :header-rows: 1
71 71
72 * - Offset 72 * - Offset
@@ -99,7 +99,7 @@ tree traversal. This format is ``ext4_dir_entry_2``, which is at most
99The directory file type is one of the following values: 99The directory file type is one of the following values:
100 100
101.. list-table:: 101.. list-table::
102 :widths: 1 79 102 :widths: 16 64
103 :header-rows: 1 103 :header-rows: 1
104 104
105 * - Value 105 * - Value
@@ -130,7 +130,7 @@ in the place where the name normally goes. The structure is
130``struct ext4_dir_entry_tail``: 130``struct ext4_dir_entry_tail``:
131 131
132.. list-table:: 132.. list-table::
133 :widths: 1 1 1 77 133 :widths: 8 8 24 40
134 :header-rows: 1 134 :header-rows: 1
135 135
136 * - Offset 136 * - Offset
@@ -212,7 +212,7 @@ The root of the htree is in ``struct dx_root``, which is the full length
212of a data block: 212of a data block:
213 213
214.. list-table:: 214.. list-table::
215 :widths: 1 1 1 77 215 :widths: 8 8 24 40
216 :header-rows: 1 216 :header-rows: 1
217 217
218 * - Offset 218 * - Offset
@@ -305,7 +305,7 @@ of a data block:
305The directory hash is one of the following values: 305The directory hash is one of the following values:
306 306
307.. list-table:: 307.. list-table::
308 :widths: 1 79 308 :widths: 16 64
309 :header-rows: 1 309 :header-rows: 1
310 310
311 * - Value 311 * - Value
@@ -327,7 +327,7 @@ Interior nodes of an htree are recorded as ``struct dx_node``, which is
327also the full length of a data block: 327also the full length of a data block:
328 328
329.. list-table:: 329.. list-table::
330 :widths: 1 1 1 77 330 :widths: 8 8 24 40
331 :header-rows: 1 331 :header-rows: 1
332 332
333 * - Offset 333 * - Offset
@@ -375,7 +375,7 @@ The hash maps that exist in both ``struct dx_root`` and
375long: 375long:
376 376
377.. list-table:: 377.. list-table::
378 :widths: 1 1 1 77 378 :widths: 8 8 24 40
379 :header-rows: 1 379 :header-rows: 1
380 380
381 * - Offset 381 * - Offset
@@ -405,7 +405,7 @@ directory index (which will ensure that there's space for the checksum.
405The dx\_tail structure is 8 bytes long and looks like this: 405The dx\_tail structure is 8 bytes long and looks like this:
406 406
407.. list-table:: 407.. list-table::
408 :widths: 1 1 1 77 408 :widths: 8 8 24 40
409 :header-rows: 1 409 :header-rows: 1
410 410
411 * - Offset 411 * - Offset
diff --git a/Documentation/filesystems/ext4/ondisk/dynamic.rst b/Documentation/filesystems/ext4/dynamic.rst
index bb0c84333341..bb0c84333341 100644
--- a/Documentation/filesystems/ext4/ondisk/dynamic.rst
+++ b/Documentation/filesystems/ext4/dynamic.rst
diff --git a/Documentation/filesystems/ext4/ondisk/eainode.rst b/Documentation/filesystems/ext4/eainode.rst
index ecc0d01a0a72..ecc0d01a0a72 100644
--- a/Documentation/filesystems/ext4/ondisk/eainode.rst
+++ b/Documentation/filesystems/ext4/eainode.rst
diff --git a/Documentation/filesystems/ext4/ext4.rst b/Documentation/filesystems/ext4/ext4.rst
deleted file mode 100644
index 9d4368d591fa..000000000000
--- a/Documentation/filesystems/ext4/ext4.rst
+++ /dev/null
@@ -1,613 +0,0 @@
1.. SPDX-License-Identifier: GPL-2.0
2
3========================
4General Information
5========================
6
7Ext4 is an advanced level of the ext3 filesystem which incorporates
8scalability and reliability enhancements for supporting large filesystems
9(64 bit) in keeping with increasing disk capacities and state-of-the-art
10feature requirements.
11
12Mailing list: linux-ext4@vger.kernel.org
13Web site: http://ext4.wiki.kernel.org
14
15
16Quick usage instructions
17========================
18
19Note: More extensive information for getting started with ext4 can be
20found at the ext4 wiki site at the URL:
21http://ext4.wiki.kernel.org/index.php/Ext4_Howto
22
23 - The latest version of e2fsprogs can be found at:
24
25 https://www.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/
26
27 or
28
29 http://sourceforge.net/project/showfiles.php?group_id=2406
30
31 or grab the latest git repository from:
32
33 https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git
34
35 - Create a new filesystem using the ext4 filesystem type:
36
37 # mke2fs -t ext4 /dev/hda1
38
39 Or to configure an existing ext3 filesystem to support extents:
40
41 # tune2fs -O extents /dev/hda1
42
43 If the filesystem was created with 128 byte inodes, it can be
44 converted to use 256 byte for greater efficiency via:
45
46 # tune2fs -I 256 /dev/hda1
47
48 - Mounting:
49
50 # mount -t ext4 /dev/hda1 /wherever
51
52 - When comparing performance with other filesystems, it's always
53 important to try multiple workloads; very often a subtle change in a
54 workload parameter can completely change the ranking of which
55 filesystems do well compared to others. When comparing versus ext3,
56 note that ext4 enables write barriers by default, while ext3 does
57 not enable write barriers by default. So it is useful to use
58 explicitly specify whether barriers are enabled or not when via the
59 '-o barriers=[0|1]' mount option for both ext3 and ext4 filesystems
60 for a fair comparison. When tuning ext3 for best benchmark numbers,
61 it is often worthwhile to try changing the data journaling mode; '-o
62 data=writeback' can be faster for some workloads. (Note however that
63 running mounted with data=writeback can potentially leave stale data
64 exposed in recently written files in case of an unclean shutdown,
65 which could be a security exposure in some situations.) Configuring
66 the filesystem with a large journal can also be helpful for
67 metadata-intensive workloads.
68
69Features
70========
71
72Currently Available
73-------------------
74
75* ability to use filesystems > 16TB (e2fsprogs support not available yet)
76* extent format reduces metadata overhead (RAM, IO for access, transactions)
77* extent format more robust in face of on-disk corruption due to magics,
78* internal redundancy in tree
79* improved file allocation (multi-block alloc)
80* lift 32000 subdirectory limit imposed by i_links_count[1]
81* nsec timestamps for mtime, atime, ctime, create time
82* inode version field on disk (NFSv4, Lustre)
83* reduced e2fsck time via uninit_bg feature
84* journal checksumming for robustness, performance
85* persistent file preallocation (e.g for streaming media, databases)
86* ability to pack bitmaps and inode tables into larger virtual groups via the
87 flex_bg feature
88* large file support
89* inode allocation using large virtual block groups via flex_bg
90* delayed allocation
91* large block (up to pagesize) support
92* efficient new ordered mode in JBD2 and ext4 (avoid using buffer head to force
93 the ordering)
94
95[1] Filesystems with a block size of 1k may see a limit imposed by the
96directory hash tree having a maximum depth of two.
97
98Options
99=======
100
101When mounting an ext4 filesystem, the following option are accepted:
102(*) == default
103
104======================= =======================================================
105Mount Option Description
106======================= =======================================================
107ro Mount filesystem read only. Note that ext4 will
108 replay the journal (and thus write to the
109 partition) even when mounted "read only". The
110 mount options "ro,noload" can be used to prevent
111 writes to the filesystem.
112
113journal_checksum Enable checksumming of the journal transactions.
114 This will allow the recovery code in e2fsck and the
115 kernel to detect corruption in the kernel. It is a
116 compatible change and will be ignored by older kernels.
117
118journal_async_commit Commit block can be written to disk without waiting
119 for descriptor blocks. If enabled older kernels cannot
120 mount the device. This will enable 'journal_checksum'
121 internally.
122
123journal_path=path
124journal_dev=devnum When the external journal device's major/minor numbers
125 have changed, these options allow the user to specify
126 the new journal location. The journal device is
127 identified through either its new major/minor numbers
128 encoded in devnum, or via a path to the device.
129
130norecovery Don't load the journal on mounting. Note that
131noload if the filesystem was not unmounted cleanly,
132 skipping the journal replay will lead to the
133 filesystem containing inconsistencies that can
134 lead to any number of problems.
135
136data=journal All data are committed into the journal prior to being
137 written into the main file system. Enabling
138 this mode will disable delayed allocation and
139 O_DIRECT support.
140
141data=ordered (*) All data are forced directly out to the main file
142 system prior to its metadata being committed to the
143 journal.
144
145data=writeback Data ordering is not preserved, data may be written
146 into the main file system after its metadata has been
147 committed to the journal.
148
149commit=nrsec (*) Ext4 can be told to sync all its data and metadata
150 every 'nrsec' seconds. The default value is 5 seconds.
151 This means that if you lose your power, you will lose
152 as much as the latest 5 seconds of work (your
153 filesystem will not be damaged though, thanks to the
154 journaling). This default value (or any low value)
155 will hurt performance, but it's good for data-safety.
156 Setting it to 0 will have the same effect as leaving
157 it at the default (5 seconds).
158 Setting it to very large values will improve
159 performance.
160
161barrier=<0|1(*)> This enables/disables the use of write barriers in
162barrier(*) the jbd code. barrier=0 disables, barrier=1 enables.
163nobarrier This also requires an IO stack which can support
164 barriers, and if jbd gets an error on a barrier
165 write, it will disable again with a warning.
166 Write barriers enforce proper on-disk ordering
167 of journal commits, making volatile disk write caches
168 safe to use, at some performance penalty. If
169 your disks are battery-backed in one way or another,
170 disabling barriers may safely improve performance.
171 The mount options "barrier" and "nobarrier" can
172 also be used to enable or disable barriers, for
173 consistency with other ext4 mount options.
174
175inode_readahead_blks=n This tuning parameter controls the maximum
176 number of inode table blocks that ext4's inode
177 table readahead algorithm will pre-read into
178 the buffer cache. The default value is 32 blocks.
179
180nouser_xattr Disables Extended User Attributes. See the
181 attr(5) manual page for more information about
182 extended attributes.
183
184noacl This option disables POSIX Access Control List
185 support. If ACL support is enabled in the kernel
186 configuration (CONFIG_EXT4_FS_POSIX_ACL), ACL is
187 enabled by default on mount. See the acl(5) manual
188 page for more information about acl.
189
190bsddf (*) Make 'df' act like BSD.
191minixdf Make 'df' act like Minix.
192
193debug Extra debugging information is sent to syslog.
194
195abort Simulate the effects of calling ext4_abort() for
196 debugging purposes. This is normally used while
197 remounting a filesystem which is already mounted.
198
199errors=remount-ro Remount the filesystem read-only on an error.
200errors=continue Keep going on a filesystem error.
201errors=panic Panic and halt the machine if an error occurs.
202 (These mount options override the errors behavior
203 specified in the superblock, which can be configured
204 using tune2fs)
205
206data_err=ignore(*) Just print an error message if an error occurs
207 in a file data buffer in ordered mode.
208data_err=abort Abort the journal if an error occurs in a file
209 data buffer in ordered mode.
210
211grpid New objects have the group ID of their parent.
212bsdgroups
213
214nogrpid (*) New objects have the group ID of their creator.
215sysvgroups
216
217resgid=n The group ID which may use the reserved blocks.
218
219resuid=n The user ID which may use the reserved blocks.
220
221sb=n Use alternate superblock at this location.
222
223quota These options are ignored by the filesystem. They
224noquota are used only by quota tools to recognize volumes
225grpquota where quota should be turned on. See documentation
226usrquota in the quota-tools package for more details
227 (http://sourceforge.net/projects/linuxquota).
228
229jqfmt=<quota type> These options tell filesystem details about quota
230usrjquota=<file> so that quota information can be properly updated
231grpjquota=<file> during journal replay. They replace the above
232 quota options. See documentation in the quota-tools
233 package for more details
234 (http://sourceforge.net/projects/linuxquota).
235
236stripe=n Number of filesystem blocks that mballoc will try
237 to use for allocation size and alignment. For RAID5/6
238 systems this should be the number of data
239 disks * RAID chunk size in file system blocks.
240
241delalloc (*) Defer block allocation until just before ext4
242 writes out the block(s) in question. This
243 allows ext4 to better allocation decisions
244 more efficiently.
245nodelalloc Disable delayed allocation. Blocks are allocated
246 when the data is copied from userspace to the
247 page cache, either via the write(2) system call
248 or when an mmap'ed page which was previously
249 unallocated is written for the first time.
250
251max_batch_time=usec Maximum amount of time ext4 should wait for
252 additional filesystem operations to be batch
253 together with a synchronous write operation.
254 Since a synchronous write operation is going to
255 force a commit and then a wait for the I/O
256 complete, it doesn't cost much, and can be a
257 huge throughput win, we wait for a small amount
258 of time to see if any other transactions can
259 piggyback on the synchronous write. The
260 algorithm used is designed to automatically tune
261 for the speed of the disk, by measuring the
262 amount of time (on average) that it takes to
263 finish committing a transaction. Call this time
264 the "commit time". If the time that the
265 transaction has been running is less than the
266 commit time, ext4 will try sleeping for the
267 commit time to see if other operations will join
268 the transaction. The commit time is capped by
269 the max_batch_time, which defaults to 15000us
270 (15ms). This optimization can be turned off
271 entirely by setting max_batch_time to 0.
272
273min_batch_time=usec This parameter sets the commit time (as
274 described above) to be at least min_batch_time.
275 It defaults to zero microseconds. Increasing
276 this parameter may improve the throughput of
277 multi-threaded, synchronous workloads on very
278 fast disks, at the cost of increasing latency.
279
280journal_ioprio=prio The I/O priority (from 0 to 7, where 0 is the
281 highest priority) which should be used for I/O
282 operations submitted by kjournald2 during a
283 commit operation. This defaults to 3, which is
284 a slightly higher priority than the default I/O
285 priority.
286
287auto_da_alloc(*) Many broken applications don't use fsync() when
288noauto_da_alloc replacing existing files via patterns such as
289 fd = open("foo.new")/write(fd,..)/close(fd)/
290 rename("foo.new", "foo"), or worse yet,
291 fd = open("foo", O_TRUNC)/write(fd,..)/close(fd).
292 If auto_da_alloc is enabled, ext4 will detect
293 the replace-via-rename and replace-via-truncate
294 patterns and force that any delayed allocation
295 blocks are allocated such that at the next
296 journal commit, in the default data=ordered
297 mode, the data blocks of the new file are forced
298 to disk before the rename() operation is
299 committed. This provides roughly the same level
300 of guarantees as ext3, and avoids the
301 "zero-length" problem that can happen when a
302 system crashes before the delayed allocation
303 blocks are forced to disk.
304
305noinit_itable Do not initialize any uninitialized inode table
306 blocks in the background. This feature may be
307 used by installation CD's so that the install
308 process can complete as quickly as possible; the
309 inode table initialization process would then be
310 deferred until the next time the file system
311 is unmounted.
312
313init_itable=n The lazy itable init code will wait n times the
314 number of milliseconds it took to zero out the
315 previous block group's inode table. This
316 minimizes the impact on the system performance
317 while file system's inode table is being initialized.
318
319discard Controls whether ext4 should issue discard/TRIM
320nodiscard(*) commands to the underlying block device when
321 blocks are freed. This is useful for SSD devices
322 and sparse/thinly-provisioned LUNs, but it is off
323 by default until sufficient testing has been done.
324
325nouid32 Disables 32-bit UIDs and GIDs. This is for
326 interoperability with older kernels which only
327 store and expect 16-bit values.
328
329block_validity(*) These options enable or disable the in-kernel
330noblock_validity facility for tracking filesystem metadata blocks
331 within internal data structures. This allows multi-
332 block allocator and other routines to notice
333 bugs or corrupted allocation bitmaps which cause
334 blocks to be allocated which overlap with
335 filesystem metadata blocks.
336
337dioread_lock Controls whether or not ext4 should use the DIO read
338dioread_nolock locking. If the dioread_nolock option is specified
339 ext4 will allocate uninitialized extent before buffer
340 write and convert the extent to initialized after IO
341 completes. This approach allows ext4 code to avoid
342 using inode mutex, which improves scalability on high
343 speed storages. However this does not work with
344 data journaling and dioread_nolock option will be
345 ignored with kernel warning. Note that dioread_nolock
346 code path is only used for extent-based files.
347 Because of the restrictions this options comprises
348 it is off by default (e.g. dioread_lock).
349
350max_dir_size_kb=n This limits the size of directories so that any
351 attempt to expand them beyond the specified
352 limit in kilobytes will cause an ENOSPC error.
353 This is useful in memory constrained
354 environments, where a very large directory can
355 cause severe performance problems or even
356 provoke the Out Of Memory killer. (For example,
357 if there is only 512mb memory available, a 176mb
358 directory may seriously cramp the system's style.)
359
360i_version Enable 64-bit inode version support. This option is
361 off by default.
362
363dax Use direct access (no page cache). See
364 Documentation/filesystems/dax.txt. Note that
365 this option is incompatible with data=journal.
366======================= =======================================================
367
368Data Mode
369=========
370There are 3 different data modes:
371
372* writeback mode
373
374 In data=writeback mode, ext4 does not journal data at all. This mode provides
375 a similar level of journaling as that of XFS, JFS, and ReiserFS in its default
376 mode - metadata journaling. A crash+recovery can cause incorrect data to
377 appear in files which were written shortly before the crash. This mode will
378 typically provide the best ext4 performance.
379
380* ordered mode
381
382 In data=ordered mode, ext4 only officially journals metadata, but it logically
383 groups metadata information related to data changes with the data blocks into
384 a single unit called a transaction. When it's time to write the new metadata
385 out to disk, the associated data blocks are written first. In general, this
386 mode performs slightly slower than writeback but significantly faster than
387 journal mode.
388
389* journal mode
390
391 data=journal mode provides full data and metadata journaling. All new data is
392 written to the journal first, and then to its final location. In the event of
393 a crash, the journal can be replayed, bringing both data and metadata into a
394 consistent state. This mode is the slowest except when data needs to be read
395 from and written to disk at the same time where it outperforms all others
396 modes. Enabling this mode will disable delayed allocation and O_DIRECT
397 support.
398
399/proc entries
400=============
401
402Information about mounted ext4 file systems can be found in
403/proc/fs/ext4. Each mounted filesystem will have a directory in
404/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
405/proc/fs/ext4/dm-0). The files in each per-device directory are shown
406in table below.
407
408Files in /proc/fs/ext4/<devname>
409
410================ =======
411 File Content
412================ =======
413 mb_groups details of multiblock allocator buddy cache of free blocks
414================ =======
415
416/sys entries
417============
418
419Information about mounted ext4 file systems can be found in
420/sys/fs/ext4. Each mounted filesystem will have a directory in
421/sys/fs/ext4 based on its device name (i.e., /sys/fs/ext4/hdc or
422/sys/fs/ext4/dm-0). The files in each per-device directory are shown
423in table below.
424
425Files in /sys/fs/ext4/<devname>:
426
427(see also Documentation/ABI/testing/sysfs-fs-ext4)
428
429============================= =================================================
430File Content
431============================= =================================================
432 delayed_allocation_blocks This file is read-only and shows the number of
433 blocks that are dirty in the page cache, but
434 which do not have their location in the
435 filesystem allocated yet.
436
437inode_goal Tuning parameter which (if non-zero) controls
438 the goal inode used by the inode allocator in
439 preference to all other allocation heuristics.
440 This is intended for debugging use only, and
441 should be 0 on production systems.
442
443inode_readahead_blks Tuning parameter which controls the maximum
444 number of inode table blocks that ext4's inode
445 table readahead algorithm will pre-read into
446 the buffer cache
447
448lifetime_write_kbytes This file is read-only and shows the number of
449 kilobytes of data that have been written to this
450 filesystem since it was created.
451
452 max_writeback_mb_bump The maximum number of megabytes the writeback
453 code will try to write out before move on to
454 another inode.
455
456 mb_group_prealloc The multiblock allocator will round up allocation
457 requests to a multiple of this tuning parameter if
458 the stripe size is not set in the ext4 superblock
459
460 mb_max_to_scan The maximum number of extents the multiblock
461 allocator will search to find the best extent
462
463 mb_min_to_scan The minimum number of extents the multiblock
464 allocator will search to find the best extent
465
466 mb_order2_req Tuning parameter which controls the minimum size
467 for requests (as a power of 2) where the buddy
468 cache is used
469
470 mb_stats Controls whether the multiblock allocator should
471 collect statistics, which are shown during the
472 unmount. 1 means to collect statistics, 0 means
473 not to collect statistics
474
475 mb_stream_req Files which have fewer blocks than this tunable
476 parameter will have their blocks allocated out
477 of a block group specific preallocation pool, so
478 that small files are packed closely together.
479 Each large file will have its blocks allocated
480 out of its own unique preallocation pool.
481
482 session_write_kbytes This file is read-only and shows the number of
483 kilobytes of data that have been written to this
484 filesystem since it was mounted.
485
486 reserved_clusters This is RW file and contains number of reserved
487 clusters in the file system which will be used
488 in the specific situations to avoid costly
489 zeroout, unexpected ENOSPC, or possible data
490 loss. The default is 2% or 4096 clusters,
491 whichever is smaller and this can be changed
492 however it can never exceed number of clusters
493 in the file system. If there is not enough space
494 for the reserved space when mounting the file
495 mount will _not_ fail.
496============================= =================================================
497
498Ioctls
499======
500
501There is some Ext4 specific functionality which can be accessed by applications
502through the system call interfaces. The list of all Ext4 specific ioctls are
503shown in the table below.
504
505Table of Ext4 specific ioctls
506
507============================= =================================================
508Ioctl Description
509============================= =================================================
510 EXT4_IOC_GETFLAGS Get additional attributes associated with inode.
511 The ioctl argument is an integer bitfield, with
512 bit values described in ext4.h. This ioctl is an
513 alias for FS_IOC_GETFLAGS.
514
515 EXT4_IOC_SETFLAGS Set additional attributes associated with inode.
516 The ioctl argument is an integer bitfield, with
517 bit values described in ext4.h. This ioctl is an
518 alias for FS_IOC_SETFLAGS.
519
520 EXT4_IOC_GETVERSION
521 EXT4_IOC_GETVERSION_OLD
522 Get the inode i_generation number stored for
523 each inode. The i_generation number is normally
524 changed only when new inode is created and it is
525 particularly useful for network filesystems. The
526 '_OLD' version of this ioctl is an alias for
527 FS_IOC_GETVERSION.
528
529 EXT4_IOC_SETVERSION
530 EXT4_IOC_SETVERSION_OLD
531 Set the inode i_generation number stored for
532 each inode. The '_OLD' version of this ioctl
533 is an alias for FS_IOC_SETVERSION.
534
535 EXT4_IOC_GROUP_EXTEND This ioctl has the same purpose as the resize
536 mount option. It allows to resize filesystem
537 to the end of the last existing block group,
538 further resize has to be done with resize2fs,
539 either online, or offline. The argument points
540 to the unsigned logn number representing the
541 filesystem new block count.
542
543 EXT4_IOC_MOVE_EXT Move the block extents from orig_fd (the one
544 this ioctl is pointing to) to the donor_fd (the
545 one specified in move_extent structure passed
546 as an argument to this ioctl). Then, exchange
547 inode metadata between orig_fd and donor_fd.
548 This is especially useful for online
549 defragmentation, because the allocator has the
550 opportunity to allocate moved blocks better,
551 ideally into one contiguous extent.
552
553 EXT4_IOC_GROUP_ADD Add a new group descriptor to an existing or
554 new group descriptor block. The new group
555 descriptor is described by ext4_new_group_input
556 structure, which is passed as an argument to
557 this ioctl. This is especially useful in
558 conjunction with EXT4_IOC_GROUP_EXTEND,
559 which allows online resize of the filesystem
560 to the end of the last existing block group.
561 Those two ioctls combined is used in userspace
562 online resize tool (e.g. resize2fs).
563
564 EXT4_IOC_MIGRATE This ioctl operates on the filesystem itself.
565 It converts (migrates) ext3 indirect block mapped
566 inode to ext4 extent mapped inode by walking
567 through indirect block mapping of the original
568 inode and converting contiguous block ranges
569 into ext4 extents of the temporary inode. Then,
570 inodes are swapped. This ioctl might help, when
571 migrating from ext3 to ext4 filesystem, however
572 suggestion is to create fresh ext4 filesystem
573 and copy data from the backup. Note, that
574 filesystem has to support extents for this ioctl
575 to work.
576
577 EXT4_IOC_ALLOC_DA_BLKS Force all of the delay allocated blocks to be
578 allocated to preserve application-expected ext3
579 behaviour. Note that this will also start
580 triggering a write of the data blocks, but this
581 behaviour may change in the future as it is
582 not necessary and has been done this way only
583 for sake of simplicity.
584
585 EXT4_IOC_RESIZE_FS Resize the filesystem to a new size. The number
586 of blocks of resized filesystem is passed in via
587 64 bit integer argument. The kernel allocates
588 bitmaps and inode table, the userspace tool thus
589 just passes the new number of blocks.
590
591 EXT4_IOC_SWAP_BOOT Swap i_blocks and associated attributes
592 (like i_blocks, i_size, i_flags, ...) from
593 the specified inode with inode
594 EXT4_BOOT_LOADER_INO (#5). This is typically
595 used to store a boot loader in a secure part of
596 the filesystem, where it can't be changed by a
597 normal user by accident.
598 The data blocks of the previous boot loader
599 will be associated with the given inode.
600============================= =================================================
601
602References
603==========
604
605kernel source: <file:fs/ext4/>
606 <file:fs/jbd2/>
607
608programs: http://e2fsprogs.sourceforge.net/
609
610useful links: http://fedoraproject.org/wiki/ext3-devel
611 http://www.bullopensource.org/ext4/
612 http://ext4.wiki.kernel.org/index.php/Main_Page
613 http://fedoraproject.org/wiki/Features/Ext4
diff --git a/Documentation/filesystems/ext4/ondisk/globals.rst b/Documentation/filesystems/ext4/globals.rst
index 368bf7662b96..368bf7662b96 100644
--- a/Documentation/filesystems/ext4/ondisk/globals.rst
+++ b/Documentation/filesystems/ext4/globals.rst
diff --git a/Documentation/filesystems/ext4/ondisk/group_descr.rst b/Documentation/filesystems/ext4/group_descr.rst
index 759827e5d2cf..0f783ed88592 100644
--- a/Documentation/filesystems/ext4/ondisk/group_descr.rst
+++ b/Documentation/filesystems/ext4/group_descr.rst
@@ -43,7 +43,7 @@ entire bitmap.
43The block group descriptor is laid out in ``struct ext4_group_desc``. 43The block group descriptor is laid out in ``struct ext4_group_desc``.
44 44
45.. list-table:: 45.. list-table::
46 :widths: 1 1 1 77 46 :widths: 8 8 24 40
47 :header-rows: 1 47 :header-rows: 1
48 48
49 * - Offset 49 * - Offset
@@ -157,7 +157,7 @@ The block group descriptor is laid out in ``struct ext4_group_desc``.
157Block group flags can be any combination of the following: 157Block group flags can be any combination of the following:
158 158
159.. list-table:: 159.. list-table::
160 :widths: 1 79 160 :widths: 16 64
161 :header-rows: 1 161 :header-rows: 1
162 162
163 * - Value 163 * - Value
diff --git a/Documentation/filesystems/ext4/ondisk/ifork.rst b/Documentation/filesystems/ext4/ifork.rst
index 5dbe3b2b121a..b9816d5a896b 100644
--- a/Documentation/filesystems/ext4/ondisk/ifork.rst
+++ b/Documentation/filesystems/ext4/ifork.rst
@@ -68,7 +68,7 @@ The extent tree header is recorded in ``struct ext4_extent_header``,
68which is 12 bytes long: 68which is 12 bytes long:
69 69
70.. list-table:: 70.. list-table::
71 :widths: 1 1 1 77 71 :widths: 8 8 24 40
72 :header-rows: 1 72 :header-rows: 1
73 73
74 * - Offset 74 * - Offset
@@ -104,7 +104,7 @@ Internal nodes of the extent tree, also known as index nodes, are
104recorded as ``struct ext4_extent_idx``, and are 12 bytes long: 104recorded as ``struct ext4_extent_idx``, and are 12 bytes long:
105 105
106.. list-table:: 106.. list-table::
107 :widths: 1 1 1 77 107 :widths: 8 8 24 40
108 :header-rows: 1 108 :header-rows: 1
109 109
110 * - Offset 110 * - Offset
@@ -134,7 +134,7 @@ Leaf nodes of the extent tree are recorded as ``struct ext4_extent``,
134and are also 12 bytes long: 134and are also 12 bytes long:
135 135
136.. list-table:: 136.. list-table::
137 :widths: 1 1 1 77 137 :widths: 8 8 24 40
138 :header-rows: 1 138 :header-rows: 1
139 139
140 * - Offset 140 * - Offset
@@ -174,7 +174,7 @@ including) the checksum itself.
174``struct ext4_extent_tail`` is 4 bytes long: 174``struct ext4_extent_tail`` is 4 bytes long:
175 175
176.. list-table:: 176.. list-table::
177 :widths: 1 1 1 77 177 :widths: 8 8 24 40
178 :header-rows: 1 178 :header-rows: 1
179 179
180 * - Offset 180 * - Offset
diff --git a/Documentation/filesystems/ext4/index.rst b/Documentation/filesystems/ext4/index.rst
index 71121605558c..3be3e54d480d 100644
--- a/Documentation/filesystems/ext4/index.rst
+++ b/Documentation/filesystems/ext4/index.rst
@@ -1,17 +1,14 @@
1.. SPDX-License-Identifier: GPL-2.0 1.. SPDX-License-Identifier: GPL-2.0
2 2
3=============== 3===================================
4ext4 Filesystem 4ext4 Data Structures and Algorithms
5=============== 5===================================
6
7General usage and on-disk artifacts writen by ext4. More documentation may
8be ported from the wiki as time permits. This should be considered the
9canonical source of information as the details here have been reviewed by
10the ext4 community.
11 6
12.. toctree:: 7.. toctree::
13 :maxdepth: 5 8 :maxdepth: 6
14 :numbered: 9 :numbered:
15 10
16 ext4 11 about.rst
17 ondisk/index 12 overview.rst
13 globals.rst
14 dynamic.rst
diff --git a/Documentation/filesystems/ext4/ondisk/inlinedata.rst b/Documentation/filesystems/ext4/inlinedata.rst
index d1075178ce0b..d1075178ce0b 100644
--- a/Documentation/filesystems/ext4/ondisk/inlinedata.rst
+++ b/Documentation/filesystems/ext4/inlinedata.rst
diff --git a/Documentation/filesystems/ext4/ondisk/inodes.rst b/Documentation/filesystems/ext4/inodes.rst
index 655ce898f3f5..6bd35e506b6f 100644
--- a/Documentation/filesystems/ext4/ondisk/inodes.rst
+++ b/Documentation/filesystems/ext4/inodes.rst
@@ -29,8 +29,9 @@ and the inode structure itself.
29The inode table entry is laid out in ``struct ext4_inode``. 29The inode table entry is laid out in ``struct ext4_inode``.
30 30
31.. list-table:: 31.. list-table::
32 :widths: 1 1 1 77 32 :widths: 8 8 24 40
33 :header-rows: 1 33 :header-rows: 1
34 :class: longtable
34 35
35 * - Offset 36 * - Offset
36 - Size 37 - Size
@@ -176,7 +177,7 @@ The inode table entry is laid out in ``struct ext4_inode``.
176The ``i_mode`` value is a combination of the following flags: 177The ``i_mode`` value is a combination of the following flags:
177 178
178.. list-table:: 179.. list-table::
179 :widths: 1 79 180 :widths: 16 64
180 :header-rows: 1 181 :header-rows: 1
181 182
182 * - Value 183 * - Value
@@ -227,7 +228,7 @@ The ``i_mode`` value is a combination of the following flags:
227The ``i_flags`` field is a combination of these values: 228The ``i_flags`` field is a combination of these values:
228 229
229.. list-table:: 230.. list-table::
230 :widths: 1 79 231 :widths: 16 64
231 :header-rows: 1 232 :header-rows: 1
232 233
233 * - Value 234 * - Value
@@ -314,7 +315,7 @@ The ``osd1`` field has multiple meanings depending on the creator:
314Linux: 315Linux:
315 316
316.. list-table:: 317.. list-table::
317 :widths: 1 1 1 77 318 :widths: 8 8 24 40
318 :header-rows: 1 319 :header-rows: 1
319 320
320 * - Offset 321 * - Offset
@@ -331,7 +332,7 @@ Linux:
331Hurd: 332Hurd:
332 333
333.. list-table:: 334.. list-table::
334 :widths: 1 1 1 77 335 :widths: 8 8 24 40
335 :header-rows: 1 336 :header-rows: 1
336 337
337 * - Offset 338 * - Offset
@@ -346,7 +347,7 @@ Hurd:
346Masix: 347Masix:
347 348
348.. list-table:: 349.. list-table::
349 :widths: 1 1 1 77 350 :widths: 8 8 24 40
350 :header-rows: 1 351 :header-rows: 1
351 352
352 * - Offset 353 * - Offset
@@ -365,7 +366,7 @@ The ``osd2`` field has multiple meanings depending on the filesystem creator:
365Linux: 366Linux:
366 367
367.. list-table:: 368.. list-table::
368 :widths: 1 1 1 77 369 :widths: 8 8 24 40
369 :header-rows: 1 370 :header-rows: 1
370 371
371 * - Offset 372 * - Offset
@@ -402,7 +403,7 @@ Linux:
402Hurd: 403Hurd:
403 404
404.. list-table:: 405.. list-table::
405 :widths: 1 1 1 77 406 :widths: 8 8 24 40
406 :header-rows: 1 407 :header-rows: 1
407 408
408 * - Offset 409 * - Offset
@@ -433,7 +434,7 @@ Hurd:
433Masix: 434Masix:
434 435
435.. list-table:: 436.. list-table::
436 :widths: 1 1 1 77 437 :widths: 8 8 24 40
437 :header-rows: 1 438 :header-rows: 1
438 439
439 * - Offset 440 * - Offset
diff --git a/Documentation/filesystems/ext4/ondisk/journal.rst b/Documentation/filesystems/ext4/journal.rst
index e7031af86876..ea613ee701f5 100644
--- a/Documentation/filesystems/ext4/ondisk/journal.rst
+++ b/Documentation/filesystems/ext4/journal.rst
@@ -48,7 +48,7 @@ Layout
48Generally speaking, the journal has this format: 48Generally speaking, the journal has this format:
49 49
50.. list-table:: 50.. list-table::
51 :widths: 1 1 78 51 :widths: 16 48 16
52 :header-rows: 1 52 :header-rows: 1
53 53
54 * - Superblock 54 * - Superblock
@@ -76,7 +76,7 @@ The journal superblock will be in the next full block after the
76superblock. 76superblock.
77 77
78.. list-table:: 78.. list-table::
79 :widths: 1 1 1 1 76 79 :widths: 12 12 12 32 12
80 :header-rows: 1 80 :header-rows: 1
81 81
82 * - 1024 bytes of padding 82 * - 1024 bytes of padding
@@ -98,7 +98,7 @@ Every block in the journal starts with a common 12-byte header
98``struct journal_header_s``: 98``struct journal_header_s``:
99 99
100.. list-table:: 100.. list-table::
101 :widths: 1 1 1 77 101 :widths: 8 8 24 40
102 :header-rows: 1 102 :header-rows: 1
103 103
104 * - Offset 104 * - Offset
@@ -124,7 +124,7 @@ Every block in the journal starts with a common 12-byte header
124The journal block type can be any one of: 124The journal block type can be any one of:
125 125
126.. list-table:: 126.. list-table::
127 :widths: 1 79 127 :widths: 16 64
128 :header-rows: 1 128 :header-rows: 1
129 129
130 * - Value 130 * - Value
@@ -154,7 +154,7 @@ The journal superblock is recorded as ``struct journal_superblock_s``,
154which is 1024 bytes long: 154which is 1024 bytes long:
155 155
156.. list-table:: 156.. list-table::
157 :widths: 1 1 1 77 157 :widths: 8 8 24 40
158 :header-rows: 1 158 :header-rows: 1
159 159
160 * - Offset 160 * - Offset
@@ -264,7 +264,7 @@ which is 1024 bytes long:
264The journal compat features are any combination of the following: 264The journal compat features are any combination of the following:
265 265
266.. list-table:: 266.. list-table::
267 :widths: 1 79 267 :widths: 16 64
268 :header-rows: 1 268 :header-rows: 1
269 269
270 * - Value 270 * - Value
@@ -278,7 +278,7 @@ The journal compat features are any combination of the following:
278The journal incompat features are any combination of the following: 278The journal incompat features are any combination of the following:
279 279
280.. list-table:: 280.. list-table::
281 :widths: 1 79 281 :widths: 16 64
282 :header-rows: 1 282 :header-rows: 1
283 283
284 * - Value 284 * - Value
@@ -306,7 +306,7 @@ Journal checksum type codes are one of the following. crc32 or crc32c are the
306most likely choices. 306most likely choices.
307 307
308.. list-table:: 308.. list-table::
309 :widths: 1 79 309 :widths: 16 64
310 :header-rows: 1 310 :header-rows: 1
311 311
312 * - Value 312 * - Value
@@ -330,7 +330,7 @@ described by a data structure, but here is the block structure anyway.
330Descriptor blocks consume at least 36 bytes, but use a full block: 330Descriptor blocks consume at least 36 bytes, but use a full block:
331 331
332.. list-table:: 332.. list-table::
333 :widths: 1 1 1 77 333 :widths: 8 8 24 40
334 :header-rows: 1 334 :header-rows: 1
335 335
336 * - Offset 336 * - Offset
@@ -355,7 +355,7 @@ defined as ``struct journal_block_tag3_s``, which looks like the
355following. The size is 16 or 32 bytes. 355following. The size is 16 or 32 bytes.
356 356
357.. list-table:: 357.. list-table::
358 :widths: 1 1 1 77 358 :widths: 8 8 24 40
359 :header-rows: 1 359 :header-rows: 1
360 360
361 * - Offset 361 * - Offset
@@ -400,7 +400,7 @@ following. The size is 16 or 32 bytes.
400The journal tag flags are any combination of the following: 400The journal tag flags are any combination of the following:
401 401
402.. list-table:: 402.. list-table::
403 :widths: 1 79 403 :widths: 16 64
404 :header-rows: 1 404 :header-rows: 1
405 405
406 * - Value 406 * - Value
@@ -421,7 +421,7 @@ is defined as ``struct journal_block_tag_s``, which looks like the
421following. The size is 8, 12, 24, or 28 bytes: 421following. The size is 8, 12, 24, or 28 bytes:
422 422
423.. list-table:: 423.. list-table::
424 :widths: 1 1 1 77 424 :widths: 8 8 24 40
425 :header-rows: 1 425 :header-rows: 1
426 426
427 * - Offset 427 * - Offset
@@ -471,7 +471,7 @@ JBD2\_FEATURE\_INCOMPAT\_CSUM\_V3 are set, the end of the block is a
471``struct jbd2_journal_block_tail``, which looks like this: 471``struct jbd2_journal_block_tail``, which looks like this:
472 472
473.. list-table:: 473.. list-table::
474 :widths: 1 1 1 77 474 :widths: 8 8 24 40
475 :header-rows: 1 475 :header-rows: 1
476 476
477 * - Offset 477 * - Offset
@@ -513,7 +513,7 @@ Revocation blocks are described in
513length, but use a full block: 513length, but use a full block:
514 514
515.. list-table:: 515.. list-table::
516 :widths: 1 1 1 77 516 :widths: 8 8 24 40
517 :header-rows: 1 517 :header-rows: 1
518 518
519 * - Offset 519 * - Offset
@@ -543,7 +543,7 @@ JBD2\_FEATURE\_INCOMPAT\_CSUM\_V3 are set, the end of the revocation
543block is a ``struct jbd2_journal_revoke_tail``, which has this format: 543block is a ``struct jbd2_journal_revoke_tail``, which has this format:
544 544
545.. list-table:: 545.. list-table::
546 :widths: 1 1 1 77 546 :widths: 8 8 24 40
547 :header-rows: 1 547 :header-rows: 1
548 548
549 * - Offset 549 * - Offset
@@ -567,7 +567,7 @@ The commit block is described by ``struct commit_header``, which is 32
567bytes long (but uses a full block): 567bytes long (but uses a full block):
568 568
569.. list-table:: 569.. list-table::
570 :widths: 1 1 1 77 570 :widths: 8 8 24 40
571 :header-rows: 1 571 :header-rows: 1
572 572
573 * - Offset 573 * - Offset
diff --git a/Documentation/filesystems/ext4/ondisk/mmp.rst b/Documentation/filesystems/ext4/mmp.rst
index b7d7a3137f80..25660981d93c 100644
--- a/Documentation/filesystems/ext4/ondisk/mmp.rst
+++ b/Documentation/filesystems/ext4/mmp.rst
@@ -32,7 +32,7 @@ The checksum is calculated against the FS UUID and the MMP structure.
32The MMP structure (``struct mmp_struct``) is as follows: 32The MMP structure (``struct mmp_struct``) is as follows:
33 33
34.. list-table:: 34.. list-table::
35 :widths: 1 1 1 77 35 :widths: 8 12 20 40
36 :header-rows: 1 36 :header-rows: 1
37 37
38 * - Offset 38 * - Offset
diff --git a/Documentation/filesystems/ext4/ondisk/index.rst b/Documentation/filesystems/ext4/ondisk/index.rst
deleted file mode 100644
index f7d082c3a435..000000000000
--- a/Documentation/filesystems/ext4/ondisk/index.rst
+++ /dev/null
@@ -1,9 +0,0 @@
1.. SPDX-License-Identifier: GPL-2.0
2
3==============================
4Data Structures and Algorithms
5==============================
6.. include:: about.rst
7.. include:: overview.rst
8.. include:: globals.rst
9.. include:: dynamic.rst
diff --git a/Documentation/filesystems/ext4/ondisk/overview.rst b/Documentation/filesystems/ext4/overview.rst
index cbab18baba12..cbab18baba12 100644
--- a/Documentation/filesystems/ext4/ondisk/overview.rst
+++ b/Documentation/filesystems/ext4/overview.rst
diff --git a/Documentation/filesystems/ext4/ondisk/special_inodes.rst b/Documentation/filesystems/ext4/special_inodes.rst
index a82f70c9baeb..9061aabba827 100644
--- a/Documentation/filesystems/ext4/ondisk/special_inodes.rst
+++ b/Documentation/filesystems/ext4/special_inodes.rst
@@ -6,7 +6,7 @@ Special inodes
6ext4 reserves some inode for special features, as follows: 6ext4 reserves some inode for special features, as follows:
7 7
8.. list-table:: 8.. list-table::
9 :widths: 1 79 9 :widths: 6 70
10 :header-rows: 1 10 :header-rows: 1
11 11
12 * - inode Number 12 * - inode Number
diff --git a/Documentation/filesystems/ext4/ondisk/super.rst b/Documentation/filesystems/ext4/super.rst
index 5f81dd87e0b9..04ff079a2acf 100644
--- a/Documentation/filesystems/ext4/ondisk/super.rst
+++ b/Documentation/filesystems/ext4/super.rst
@@ -19,7 +19,7 @@ The ext4 superblock is laid out as follows in
19``struct ext4_super_block``: 19``struct ext4_super_block``:
20 20
21.. list-table:: 21.. list-table::
22 :widths: 1 1 1 77 22 :widths: 8 8 24 40
23 :header-rows: 1 23 :header-rows: 1
24 24
25 * - Offset 25 * - Offset
@@ -483,7 +483,7 @@ The ext4 superblock is laid out as follows in
483The superblock state is some combination of the following: 483The superblock state is some combination of the following:
484 484
485.. list-table:: 485.. list-table::
486 :widths: 1 79 486 :widths: 8 72
487 :header-rows: 1 487 :header-rows: 1
488 488
489 * - Value 489 * - Value
@@ -500,7 +500,7 @@ The superblock state is some combination of the following:
500The superblock error policy is one of the following: 500The superblock error policy is one of the following:
501 501
502.. list-table:: 502.. list-table::
503 :widths: 1 79 503 :widths: 8 72
504 :header-rows: 1 504 :header-rows: 1
505 505
506 * - Value 506 * - Value
@@ -517,7 +517,7 @@ The superblock error policy is one of the following:
517The filesystem creator is one of the following: 517The filesystem creator is one of the following:
518 518
519.. list-table:: 519.. list-table::
520 :widths: 1 79 520 :widths: 8 72
521 :header-rows: 1 521 :header-rows: 1
522 522
523 * - Value 523 * - Value
@@ -538,7 +538,7 @@ The filesystem creator is one of the following:
538The superblock revision is one of the following: 538The superblock revision is one of the following:
539 539
540.. list-table:: 540.. list-table::
541 :widths: 1 79 541 :widths: 8 72
542 :header-rows: 1 542 :header-rows: 1
543 543
544 * - Value 544 * - Value
@@ -556,7 +556,7 @@ The superblock compatible features field is a combination of any of the
556following: 556following:
557 557
558.. list-table:: 558.. list-table::
559 :widths: 1 79 559 :widths: 16 64
560 :header-rows: 1 560 :header-rows: 1
561 561
562 * - Value 562 * - Value
@@ -595,7 +595,7 @@ The superblock incompatible features field is a combination of any of the
595following: 595following:
596 596
597.. list-table:: 597.. list-table::
598 :widths: 1 79 598 :widths: 16 64
599 :header-rows: 1 599 :header-rows: 1
600 600
601 * - Value 601 * - Value
@@ -647,7 +647,7 @@ The superblock read-only compatible features field is a combination of any of
647the following: 647the following:
648 648
649.. list-table:: 649.. list-table::
650 :widths: 1 79 650 :widths: 16 64
651 :header-rows: 1 651 :header-rows: 1
652 652
653 * - Value 653 * - Value
@@ -702,7 +702,7 @@ the following:
702The ``s_def_hash_version`` field is one of the following: 702The ``s_def_hash_version`` field is one of the following:
703 703
704.. list-table:: 704.. list-table::
705 :widths: 1 79 705 :widths: 8 72
706 :header-rows: 1 706 :header-rows: 1
707 707
708 * - Value 708 * - Value
@@ -725,7 +725,7 @@ The ``s_def_hash_version`` field is one of the following:
725The ``s_default_mount_opts`` field is any combination of the following: 725The ``s_default_mount_opts`` field is any combination of the following:
726 726
727.. list-table:: 727.. list-table::
728 :widths: 1 79 728 :widths: 8 72
729 :header-rows: 1 729 :header-rows: 1
730 730
731 * - Value 731 * - Value
@@ -767,7 +767,7 @@ The ``s_default_mount_opts`` field is any combination of the following:
767The ``s_flags`` field is any combination of the following: 767The ``s_flags`` field is any combination of the following:
768 768
769.. list-table:: 769.. list-table::
770 :widths: 1 79 770 :widths: 8 72
771 :header-rows: 1 771 :header-rows: 1
772 772
773 * - Value 773 * - Value
@@ -784,7 +784,7 @@ The ``s_flags`` field is any combination of the following:
784The ``s_encrypt_algos`` list can contain any of the following: 784The ``s_encrypt_algos`` list can contain any of the following:
785 785
786.. list-table:: 786.. list-table::
787 :widths: 1 79 787 :widths: 8 72
788 :header-rows: 1 788 :header-rows: 1
789 789
790 * - Value 790 * - Value
generated by cgit v1.2.2 (git 2.25.0) at 2025-09-06 01:50:42 -0400