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fast_commit.c
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fast_commit.c
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// SPDX-License-Identifier: GPL-2.0
/*
* fs/ext4/fast_commit.c
*
* Written by Harshad Shirwadkar <harshadshirwadkar@gmail.com>
*
* Ext4 fast commits routines.
*/
#include "ext4.h"
#include "ext4_jbd2.h"
#include "ext4_extents.h"
#include "mballoc.h"
/*
* Ext4 Fast Commits
* -----------------
*
* Ext4 fast commits implement fine grained journalling for Ext4.
*
* Fast commits are organized as a log of tag-length-value (TLV) structs. (See
* struct ext4_fc_tl). Each TLV contains some delta that is replayed TLV by
* TLV during the recovery phase. For the scenarios for which we currently
* don't have replay code, fast commit falls back to full commits.
* Fast commits record delta in one of the following three categories.
*
* (A) Directory entry updates:
*
* - EXT4_FC_TAG_UNLINK - records directory entry unlink
* - EXT4_FC_TAG_LINK - records directory entry link
* - EXT4_FC_TAG_CREAT - records inode and directory entry creation
*
* (B) File specific data range updates:
*
* - EXT4_FC_TAG_ADD_RANGE - records addition of new blocks to an inode
* - EXT4_FC_TAG_DEL_RANGE - records deletion of blocks from an inode
*
* (C) Inode metadata (mtime / ctime etc):
*
* - EXT4_FC_TAG_INODE - record the inode that should be replayed
* during recovery. Note that iblocks field is
* not replayed and instead derived during
* replay.
* Commit Operation
* ----------------
* With fast commits, we maintain all the directory entry operations in the
* order in which they are issued in an in-memory queue. This queue is flushed
* to disk during the commit operation. We also maintain a list of inodes
* that need to be committed during a fast commit in another in memory queue of
* inodes. During the commit operation, we commit in the following order:
*
* [1] Lock inodes for any further data updates by setting COMMITTING state
* [2] Submit data buffers of all the inodes
* [3] Wait for [2] to complete
* [4] Commit all the directory entry updates in the fast commit space
* [5] Commit all the changed inode structures
* [6] Write tail tag (this tag ensures the atomicity, please read the following
* section for more details).
* [7] Wait for [4], [5] and [6] to complete.
*
* All the inode updates must call ext4_fc_start_update() before starting an
* update. If such an ongoing update is present, fast commit waits for it to
* complete. The completion of such an update is marked by
* ext4_fc_stop_update().
*
* Fast Commit Ineligibility
* -------------------------
*
* Not all operations are supported by fast commits today (e.g extended
* attributes). Fast commit ineligibility is marked by calling
* ext4_fc_mark_ineligible(): This makes next fast commit operation to fall back
* to full commit.
*
* Atomicity of commits
* --------------------
* In order to guarantee atomicity during the commit operation, fast commit
* uses "EXT4_FC_TAG_TAIL" tag that marks a fast commit as complete. Tail
* tag contains CRC of the contents and TID of the transaction after which
* this fast commit should be applied. Recovery code replays fast commit
* logs only if there's at least 1 valid tail present. For every fast commit
* operation, there is 1 tail. This means, we may end up with multiple tails
* in the fast commit space. Here's an example:
*
* - Create a new file A and remove existing file B
* - fsync()
* - Append contents to file A
* - Truncate file A
* - fsync()
*
* The fast commit space at the end of above operations would look like this:
* [HEAD] [CREAT A] [UNLINK B] [TAIL] [ADD_RANGE A] [DEL_RANGE A] [TAIL]
* |<--- Fast Commit 1 --->|<--- Fast Commit 2 ---->|
*
* Replay code should thus check for all the valid tails in the FC area.
*
* Fast Commit Replay Idempotence
* ------------------------------
*
* Fast commits tags are idempotent in nature provided the recovery code follows
* certain rules. The guiding principle that the commit path follows while
* committing is that it stores the result of a particular operation instead of
* storing the procedure.
*
* Let's consider this rename operation: 'mv /a /b'. Let's assume dirent '/a'
* was associated with inode 10. During fast commit, instead of storing this
* operation as a procedure "rename a to b", we store the resulting file system
* state as a "series" of outcomes:
*
* - Link dirent b to inode 10
* - Unlink dirent a
* - Inode <10> with valid refcount
*
* Now when recovery code runs, it needs "enforce" this state on the file
* system. This is what guarantees idempotence of fast commit replay.
*
* Let's take an example of a procedure that is not idempotent and see how fast
* commits make it idempotent. Consider following sequence of operations:
*
* rm A; mv B A; read A
* (x) (y) (z)
*
* (x), (y) and (z) are the points at which we can crash. If we store this
* sequence of operations as is then the replay is not idempotent. Let's say
* while in replay, we crash at (z). During the second replay, file A (which was
* actually created as a result of "mv B A" operation) would get deleted. Thus,
* file named A would be absent when we try to read A. So, this sequence of
* operations is not idempotent. However, as mentioned above, instead of storing
* the procedure fast commits store the outcome of each procedure. Thus the fast
* commit log for above procedure would be as follows:
*
* (Let's assume dirent A was linked to inode 10 and dirent B was linked to
* inode 11 before the replay)
*
* [Unlink A] [Link A to inode 11] [Unlink B] [Inode 11]
* (w) (x) (y) (z)
*
* If we crash at (z), we will have file A linked to inode 11. During the second
* replay, we will remove file A (inode 11). But we will create it back and make
* it point to inode 11. We won't find B, so we'll just skip that step. At this
* point, the refcount for inode 11 is not reliable, but that gets fixed by the
* replay of last inode 11 tag. Crashes at points (w), (x) and (y) get handled
* similarly. Thus, by converting a non-idempotent procedure into a series of
* idempotent outcomes, fast commits ensured idempotence during the replay.
*
* TODOs
* -----
*
* 0) Fast commit replay path hardening: Fast commit replay code should use
* journal handles to make sure all the updates it does during the replay
* path are atomic. With that if we crash during fast commit replay, after
* trying to do recovery again, we will find a file system where fast commit
* area is invalid (because new full commit would be found). In order to deal
* with that, fast commit replay code should ensure that the "FC_REPLAY"
* superblock state is persisted before starting the replay, so that after
* the crash, fast commit recovery code can look at that flag and perform
* fast commit recovery even if that area is invalidated by later full
* commits.
*
* 1) Fast commit's commit path locks the entire file system during fast
* commit. This has significant performance penalty. Instead of that, we
* should use ext4_fc_start/stop_update functions to start inode level
* updates from ext4_journal_start/stop. Once we do that we can drop file
* system locking during commit path.
*
* 2) Handle more ineligible cases.
*/
#include <trace/events/ext4.h>
static struct kmem_cache *ext4_fc_dentry_cachep;
static void ext4_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
{
BUFFER_TRACE(bh, "");
if (uptodate) {
ext4_debug("%s: Block %lld up-to-date",
__func__, bh->b_blocknr);
set_buffer_uptodate(bh);
} else {
ext4_debug("%s: Block %lld not up-to-date",
__func__, bh->b_blocknr);
clear_buffer_uptodate(bh);
}
unlock_buffer(bh);
}
static inline void ext4_fc_reset_inode(struct inode *inode)
{
struct ext4_inode_info *ei = EXT4_I(inode);
ei->i_fc_lblk_start = 0;
ei->i_fc_lblk_len = 0;
}
void ext4_fc_init_inode(struct inode *inode)
{
struct ext4_inode_info *ei = EXT4_I(inode);
ext4_fc_reset_inode(inode);
ext4_clear_inode_state(inode, EXT4_STATE_FC_COMMITTING);
INIT_LIST_HEAD(&ei->i_fc_list);
INIT_LIST_HEAD(&ei->i_fc_dilist);
init_waitqueue_head(&ei->i_fc_wait);
atomic_set(&ei->i_fc_updates, 0);
}
/* This function must be called with sbi->s_fc_lock held. */
static void ext4_fc_wait_committing_inode(struct inode *inode)
__releases(&EXT4_SB(inode->i_sb)->s_fc_lock)
{
wait_queue_head_t *wq;
struct ext4_inode_info *ei = EXT4_I(inode);
#if (BITS_PER_LONG < 64)
DEFINE_WAIT_BIT(wait, &ei->i_state_flags,
EXT4_STATE_FC_COMMITTING);
wq = bit_waitqueue(&ei->i_state_flags,
EXT4_STATE_FC_COMMITTING);
#else
DEFINE_WAIT_BIT(wait, &ei->i_flags,
EXT4_STATE_FC_COMMITTING);
wq = bit_waitqueue(&ei->i_flags,
EXT4_STATE_FC_COMMITTING);
#endif
lockdep_assert_held(&EXT4_SB(inode->i_sb)->s_fc_lock);
prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
spin_unlock(&EXT4_SB(inode->i_sb)->s_fc_lock);
schedule();
finish_wait(wq, &wait.wq_entry);
}
/*
* Inform Ext4's fast about start of an inode update
*
* This function is called by the high level call VFS callbacks before
* performing any inode update. This function blocks if there's an ongoing
* fast commit on the inode in question.
*/
void ext4_fc_start_update(struct inode *inode)
{
struct ext4_inode_info *ei = EXT4_I(inode);
if (!test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT) ||
(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY))
return;
restart:
spin_lock(&EXT4_SB(inode->i_sb)->s_fc_lock);
if (list_empty(&ei->i_fc_list))
goto out;
if (ext4_test_inode_state(inode, EXT4_STATE_FC_COMMITTING)) {
ext4_fc_wait_committing_inode(inode);
goto restart;
}
out:
atomic_inc(&ei->i_fc_updates);
spin_unlock(&EXT4_SB(inode->i_sb)->s_fc_lock);
}
/*
* Stop inode update and wake up waiting fast commits if any.
*/
void ext4_fc_stop_update(struct inode *inode)
{
struct ext4_inode_info *ei = EXT4_I(inode);
if (!test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT) ||
(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY))
return;
if (atomic_dec_and_test(&ei->i_fc_updates))
wake_up_all(&ei->i_fc_wait);
}
/*
* Remove inode from fast commit list. If the inode is being committed
* we wait until inode commit is done.
*/
void ext4_fc_del(struct inode *inode)
{
struct ext4_inode_info *ei = EXT4_I(inode);
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct ext4_fc_dentry_update *fc_dentry;
if (!test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT) ||
(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY))
return;
restart:
spin_lock(&EXT4_SB(inode->i_sb)->s_fc_lock);
if (list_empty(&ei->i_fc_list) && list_empty(&ei->i_fc_dilist)) {
spin_unlock(&EXT4_SB(inode->i_sb)->s_fc_lock);
return;
}
if (ext4_test_inode_state(inode, EXT4_STATE_FC_COMMITTING)) {
ext4_fc_wait_committing_inode(inode);
goto restart;
}
if (!list_empty(&ei->i_fc_list))
list_del_init(&ei->i_fc_list);
/*
* Since this inode is getting removed, let's also remove all FC
* dentry create references, since it is not needed to log it anyways.
*/
if (list_empty(&ei->i_fc_dilist)) {
spin_unlock(&sbi->s_fc_lock);
return;
}
fc_dentry = list_first_entry(&ei->i_fc_dilist, struct ext4_fc_dentry_update, fcd_dilist);
WARN_ON(fc_dentry->fcd_op != EXT4_FC_TAG_CREAT);
list_del_init(&fc_dentry->fcd_list);
list_del_init(&fc_dentry->fcd_dilist);
WARN_ON(!list_empty(&ei->i_fc_dilist));
spin_unlock(&sbi->s_fc_lock);
if (fc_dentry->fcd_name.name &&
fc_dentry->fcd_name.len > DNAME_INLINE_LEN)
kfree(fc_dentry->fcd_name.name);
kmem_cache_free(ext4_fc_dentry_cachep, fc_dentry);
return;
}
/*
* Mark file system as fast commit ineligible, and record latest
* ineligible transaction tid. This means until the recorded
* transaction, commit operation would result in a full jbd2 commit.
*/
void ext4_fc_mark_ineligible(struct super_block *sb, int reason, handle_t *handle)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
tid_t tid;
if (!test_opt2(sb, JOURNAL_FAST_COMMIT) ||
(EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY))
return;
ext4_set_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);
if (handle && !IS_ERR(handle))
tid = handle->h_transaction->t_tid;
else {
read_lock(&sbi->s_journal->j_state_lock);
tid = sbi->s_journal->j_running_transaction ?
sbi->s_journal->j_running_transaction->t_tid : 0;
read_unlock(&sbi->s_journal->j_state_lock);
}
spin_lock(&sbi->s_fc_lock);
if (sbi->s_fc_ineligible_tid < tid)
sbi->s_fc_ineligible_tid = tid;
spin_unlock(&sbi->s_fc_lock);
WARN_ON(reason >= EXT4_FC_REASON_MAX);
sbi->s_fc_stats.fc_ineligible_reason_count[reason]++;
}
/*
* Generic fast commit tracking function. If this is the first time this we are
* called after a full commit, we initialize fast commit fields and then call
* __fc_track_fn() with update = 0. If we have already been called after a full
* commit, we pass update = 1. Based on that, the track function can determine
* if it needs to track a field for the first time or if it needs to just
* update the previously tracked value.
*
* If enqueue is set, this function enqueues the inode in fast commit list.
*/
static int ext4_fc_track_template(
handle_t *handle, struct inode *inode,
int (*__fc_track_fn)(struct inode *, void *, bool),
void *args, int enqueue)
{
bool update = false;
struct ext4_inode_info *ei = EXT4_I(inode);
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
tid_t tid = 0;
int ret;
tid = handle->h_transaction->t_tid;
mutex_lock(&ei->i_fc_lock);
if (tid == ei->i_sync_tid) {
update = true;
} else {
ext4_fc_reset_inode(inode);
ei->i_sync_tid = tid;
}
ret = __fc_track_fn(inode, args, update);
mutex_unlock(&ei->i_fc_lock);
if (!enqueue)
return ret;
spin_lock(&sbi->s_fc_lock);
if (list_empty(&EXT4_I(inode)->i_fc_list))
list_add_tail(&EXT4_I(inode)->i_fc_list,
(sbi->s_journal->j_flags & JBD2_FULL_COMMIT_ONGOING ||
sbi->s_journal->j_flags & JBD2_FAST_COMMIT_ONGOING) ?
&sbi->s_fc_q[FC_Q_STAGING] :
&sbi->s_fc_q[FC_Q_MAIN]);
spin_unlock(&sbi->s_fc_lock);
return ret;
}
struct __track_dentry_update_args {
struct dentry *dentry;
int op;
};
/* __track_fn for directory entry updates. Called with ei->i_fc_lock. */
static int __track_dentry_update(struct inode *inode, void *arg, bool update)
{
struct ext4_fc_dentry_update *node;
struct ext4_inode_info *ei = EXT4_I(inode);
struct __track_dentry_update_args *dentry_update =
(struct __track_dentry_update_args *)arg;
struct dentry *dentry = dentry_update->dentry;
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
mutex_unlock(&ei->i_fc_lock);
node = kmem_cache_alloc(ext4_fc_dentry_cachep, GFP_NOFS);
if (!node) {
ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_NOMEM, NULL);
mutex_lock(&ei->i_fc_lock);
return -ENOMEM;
}
node->fcd_op = dentry_update->op;
node->fcd_parent = dentry->d_parent->d_inode->i_ino;
node->fcd_ino = inode->i_ino;
if (dentry->d_name.len > DNAME_INLINE_LEN) {
node->fcd_name.name = kmalloc(dentry->d_name.len, GFP_NOFS);
if (!node->fcd_name.name) {
kmem_cache_free(ext4_fc_dentry_cachep, node);
ext4_fc_mark_ineligible(inode->i_sb,
EXT4_FC_REASON_NOMEM, NULL);
mutex_lock(&ei->i_fc_lock);
return -ENOMEM;
}
memcpy((u8 *)node->fcd_name.name, dentry->d_name.name,
dentry->d_name.len);
} else {
memcpy(node->fcd_iname, dentry->d_name.name,
dentry->d_name.len);
node->fcd_name.name = node->fcd_iname;
}
node->fcd_name.len = dentry->d_name.len;
INIT_LIST_HEAD(&node->fcd_dilist);
spin_lock(&sbi->s_fc_lock);
if (sbi->s_journal->j_flags & JBD2_FULL_COMMIT_ONGOING ||
sbi->s_journal->j_flags & JBD2_FAST_COMMIT_ONGOING)
list_add_tail(&node->fcd_list,
&sbi->s_fc_dentry_q[FC_Q_STAGING]);
else
list_add_tail(&node->fcd_list, &sbi->s_fc_dentry_q[FC_Q_MAIN]);
/*
* This helps us keep a track of all fc_dentry updates which is part of
* this ext4 inode. So in case the inode is getting unlinked, before
* even we get a chance to fsync, we could remove all fc_dentry
* references while evicting the inode in ext4_fc_del().
* Also with this, we don't need to loop over all the inodes in
* sbi->s_fc_q to get the corresponding inode in
* ext4_fc_commit_dentry_updates().
*/
if (dentry_update->op == EXT4_FC_TAG_CREAT) {
WARN_ON(!list_empty(&ei->i_fc_dilist));
list_add_tail(&node->fcd_dilist, &ei->i_fc_dilist);
}
spin_unlock(&sbi->s_fc_lock);
mutex_lock(&ei->i_fc_lock);
return 0;
}
void __ext4_fc_track_unlink(handle_t *handle,
struct inode *inode, struct dentry *dentry)
{
struct __track_dentry_update_args args;
int ret;
args.dentry = dentry;
args.op = EXT4_FC_TAG_UNLINK;
ret = ext4_fc_track_template(handle, inode, __track_dentry_update,
(void *)&args, 0);
trace_ext4_fc_track_unlink(handle, inode, dentry, ret);
}
void ext4_fc_track_unlink(handle_t *handle, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
if (!test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT) ||
(sbi->s_mount_state & EXT4_FC_REPLAY))
return;
if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FC_INELIGIBLE))
return;
__ext4_fc_track_unlink(handle, inode, dentry);
}
void __ext4_fc_track_link(handle_t *handle,
struct inode *inode, struct dentry *dentry)
{
struct __track_dentry_update_args args;
int ret;
args.dentry = dentry;
args.op = EXT4_FC_TAG_LINK;
ret = ext4_fc_track_template(handle, inode, __track_dentry_update,
(void *)&args, 0);
trace_ext4_fc_track_link(handle, inode, dentry, ret);
}
void ext4_fc_track_link(handle_t *handle, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
if (!test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT) ||
(sbi->s_mount_state & EXT4_FC_REPLAY))
return;
if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FC_INELIGIBLE))
return;
__ext4_fc_track_link(handle, inode, dentry);
}
void __ext4_fc_track_create(handle_t *handle, struct inode *inode,
struct dentry *dentry)
{
struct __track_dentry_update_args args;
int ret;
args.dentry = dentry;
args.op = EXT4_FC_TAG_CREAT;
ret = ext4_fc_track_template(handle, inode, __track_dentry_update,
(void *)&args, 0);
trace_ext4_fc_track_create(handle, inode, dentry, ret);
}
void ext4_fc_track_create(handle_t *handle, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
if (!test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT) ||
(sbi->s_mount_state & EXT4_FC_REPLAY))
return;
if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FC_INELIGIBLE))
return;
__ext4_fc_track_create(handle, inode, dentry);
}
/* __track_fn for inode tracking */
static int __track_inode(struct inode *inode, void *arg, bool update)
{
if (update)
return -EEXIST;
EXT4_I(inode)->i_fc_lblk_len = 0;
return 0;
}
void ext4_fc_track_inode(handle_t *handle, struct inode *inode)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
int ret;
if (S_ISDIR(inode->i_mode))
return;
if (ext4_should_journal_data(inode)) {
ext4_fc_mark_ineligible(inode->i_sb,
EXT4_FC_REASON_INODE_JOURNAL_DATA, handle);
return;
}
if (!test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT) ||
(sbi->s_mount_state & EXT4_FC_REPLAY))
return;
if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FC_INELIGIBLE))
return;
ret = ext4_fc_track_template(handle, inode, __track_inode, NULL, 1);
trace_ext4_fc_track_inode(handle, inode, ret);
}
struct __track_range_args {
ext4_lblk_t start, end;
};
/* __track_fn for tracking data updates */
static int __track_range(struct inode *inode, void *arg, bool update)
{
struct ext4_inode_info *ei = EXT4_I(inode);
ext4_lblk_t oldstart;
struct __track_range_args *__arg =
(struct __track_range_args *)arg;
if (inode->i_ino < EXT4_FIRST_INO(inode->i_sb)) {
ext4_debug("Special inode %ld being modified\n", inode->i_ino);
return -ECANCELED;
}
oldstart = ei->i_fc_lblk_start;
if (update && ei->i_fc_lblk_len > 0) {
ei->i_fc_lblk_start = min(ei->i_fc_lblk_start, __arg->start);
ei->i_fc_lblk_len =
max(oldstart + ei->i_fc_lblk_len - 1, __arg->end) -
ei->i_fc_lblk_start + 1;
} else {
ei->i_fc_lblk_start = __arg->start;
ei->i_fc_lblk_len = __arg->end - __arg->start + 1;
}
return 0;
}
void ext4_fc_track_range(handle_t *handle, struct inode *inode, ext4_lblk_t start,
ext4_lblk_t end)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct __track_range_args args;
int ret;
if (S_ISDIR(inode->i_mode))
return;
if (!test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT) ||
(sbi->s_mount_state & EXT4_FC_REPLAY))
return;
if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FC_INELIGIBLE))
return;
args.start = start;
args.end = end;
ret = ext4_fc_track_template(handle, inode, __track_range, &args, 1);
trace_ext4_fc_track_range(handle, inode, start, end, ret);
}
static void ext4_fc_submit_bh(struct super_block *sb, bool is_tail)
{
blk_opf_t write_flags = REQ_SYNC;
struct buffer_head *bh = EXT4_SB(sb)->s_fc_bh;
/* Add REQ_FUA | REQ_PREFLUSH only its tail */
if (test_opt(sb, BARRIER) && is_tail)
write_flags |= REQ_FUA | REQ_PREFLUSH;
lock_buffer(bh);
set_buffer_dirty(bh);
set_buffer_uptodate(bh);
bh->b_end_io = ext4_end_buffer_io_sync;
submit_bh(REQ_OP_WRITE | write_flags, bh);
EXT4_SB(sb)->s_fc_bh = NULL;
}
/* Ext4 commit path routines */
/* memzero and update CRC */
static void *ext4_fc_memzero(struct super_block *sb, void *dst, int len,
u32 *crc)
{
void *ret;
ret = memset(dst, 0, len);
if (crc)
*crc = ext4_chksum(EXT4_SB(sb), *crc, dst, len);
return ret;
}
/*
* Allocate len bytes on a fast commit buffer.
*
* During the commit time this function is used to manage fast commit
* block space. We don't split a fast commit log onto different
* blocks. So this function makes sure that if there's not enough space
* on the current block, the remaining space in the current block is
* marked as unused by adding EXT4_FC_TAG_PAD tag. In that case,
* new block is from jbd2 and CRC is updated to reflect the padding
* we added.
*/
static u8 *ext4_fc_reserve_space(struct super_block *sb, int len, u32 *crc)
{
struct ext4_fc_tl *tl;
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct buffer_head *bh;
int bsize = sbi->s_journal->j_blocksize;
int ret, off = sbi->s_fc_bytes % bsize;
int pad_len;
/*
* After allocating len, we should have space at least for a 0 byte
* padding.
*/
if (len + EXT4_FC_TAG_BASE_LEN > bsize)
return NULL;
if (bsize - off - 1 > len + EXT4_FC_TAG_BASE_LEN) {
/*
* Only allocate from current buffer if we have enough space for
* this request AND we have space to add a zero byte padding.
*/
if (!sbi->s_fc_bh) {
ret = jbd2_fc_get_buf(EXT4_SB(sb)->s_journal, &bh);
if (ret)
return NULL;
sbi->s_fc_bh = bh;
}
sbi->s_fc_bytes += len;
return sbi->s_fc_bh->b_data + off;
}
/* Need to add PAD tag */
tl = (struct ext4_fc_tl *)(sbi->s_fc_bh->b_data + off);
tl->fc_tag = cpu_to_le16(EXT4_FC_TAG_PAD);
pad_len = bsize - off - 1 - EXT4_FC_TAG_BASE_LEN;
tl->fc_len = cpu_to_le16(pad_len);
if (crc)
*crc = ext4_chksum(sbi, *crc, tl, EXT4_FC_TAG_BASE_LEN);
if (pad_len > 0)
ext4_fc_memzero(sb, tl + 1, pad_len, crc);
ext4_fc_submit_bh(sb, false);
ret = jbd2_fc_get_buf(EXT4_SB(sb)->s_journal, &bh);
if (ret)
return NULL;
sbi->s_fc_bh = bh;
sbi->s_fc_bytes = (sbi->s_fc_bytes / bsize + 1) * bsize + len;
return sbi->s_fc_bh->b_data;
}
/* memcpy to fc reserved space and update CRC */
static void *ext4_fc_memcpy(struct super_block *sb, void *dst, const void *src,
int len, u32 *crc)
{
if (crc)
*crc = ext4_chksum(EXT4_SB(sb), *crc, src, len);
return memcpy(dst, src, len);
}
/*
* Complete a fast commit by writing tail tag.
*
* Writing tail tag marks the end of a fast commit. In order to guarantee
* atomicity, after writing tail tag, even if there's space remaining
* in the block, next commit shouldn't use it. That's why tail tag
* has the length as that of the remaining space on the block.
*/
static int ext4_fc_write_tail(struct super_block *sb, u32 crc)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct ext4_fc_tl tl;
struct ext4_fc_tail tail;
int off, bsize = sbi->s_journal->j_blocksize;
u8 *dst;
/*
* ext4_fc_reserve_space takes care of allocating an extra block if
* there's no enough space on this block for accommodating this tail.
*/
dst = ext4_fc_reserve_space(sb, EXT4_FC_TAG_BASE_LEN + sizeof(tail), &crc);
if (!dst)
return -ENOSPC;
off = sbi->s_fc_bytes % bsize;
tl.fc_tag = cpu_to_le16(EXT4_FC_TAG_TAIL);
tl.fc_len = cpu_to_le16(bsize - off - 1 + sizeof(struct ext4_fc_tail));
sbi->s_fc_bytes = round_up(sbi->s_fc_bytes, bsize);
ext4_fc_memcpy(sb, dst, &tl, EXT4_FC_TAG_BASE_LEN, &crc);
dst += EXT4_FC_TAG_BASE_LEN;
tail.fc_tid = cpu_to_le32(sbi->s_journal->j_running_transaction->t_tid);
ext4_fc_memcpy(sb, dst, &tail.fc_tid, sizeof(tail.fc_tid), &crc);
dst += sizeof(tail.fc_tid);
tail.fc_crc = cpu_to_le32(crc);
ext4_fc_memcpy(sb, dst, &tail.fc_crc, sizeof(tail.fc_crc), NULL);
ext4_fc_submit_bh(sb, true);
return 0;
}
/*
* Adds tag, length, value and updates CRC. Returns true if tlv was added.
* Returns false if there's not enough space.
*/
static bool ext4_fc_add_tlv(struct super_block *sb, u16 tag, u16 len, u8 *val,
u32 *crc)
{
struct ext4_fc_tl tl;
u8 *dst;
dst = ext4_fc_reserve_space(sb, EXT4_FC_TAG_BASE_LEN + len, crc);
if (!dst)
return false;
tl.fc_tag = cpu_to_le16(tag);
tl.fc_len = cpu_to_le16(len);
ext4_fc_memcpy(sb, dst, &tl, EXT4_FC_TAG_BASE_LEN, crc);
ext4_fc_memcpy(sb, dst + EXT4_FC_TAG_BASE_LEN, val, len, crc);
return true;
}
/* Same as above, but adds dentry tlv. */
static bool ext4_fc_add_dentry_tlv(struct super_block *sb, u32 *crc,
struct ext4_fc_dentry_update *fc_dentry)
{
struct ext4_fc_dentry_info fcd;
struct ext4_fc_tl tl;
int dlen = fc_dentry->fcd_name.len;
u8 *dst = ext4_fc_reserve_space(sb,
EXT4_FC_TAG_BASE_LEN + sizeof(fcd) + dlen, crc);
if (!dst)
return false;
fcd.fc_parent_ino = cpu_to_le32(fc_dentry->fcd_parent);
fcd.fc_ino = cpu_to_le32(fc_dentry->fcd_ino);
tl.fc_tag = cpu_to_le16(fc_dentry->fcd_op);
tl.fc_len = cpu_to_le16(sizeof(fcd) + dlen);
ext4_fc_memcpy(sb, dst, &tl, EXT4_FC_TAG_BASE_LEN, crc);
dst += EXT4_FC_TAG_BASE_LEN;
ext4_fc_memcpy(sb, dst, &fcd, sizeof(fcd), crc);
dst += sizeof(fcd);
ext4_fc_memcpy(sb, dst, fc_dentry->fcd_name.name, dlen, crc);
return true;
}
/*
* Writes inode in the fast commit space under TLV with tag @tag.
* Returns 0 on success, error on failure.
*/
static int ext4_fc_write_inode(struct inode *inode, u32 *crc)
{
struct ext4_inode_info *ei = EXT4_I(inode);
int inode_len = EXT4_GOOD_OLD_INODE_SIZE;
int ret;
struct ext4_iloc iloc;
struct ext4_fc_inode fc_inode;
struct ext4_fc_tl tl;
u8 *dst;
ret = ext4_get_inode_loc(inode, &iloc);
if (ret)
return ret;
if (ext4_test_inode_flag(inode, EXT4_INODE_INLINE_DATA))
inode_len = EXT4_INODE_SIZE(inode->i_sb);
else if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE)
inode_len += ei->i_extra_isize;
fc_inode.fc_ino = cpu_to_le32(inode->i_ino);
tl.fc_tag = cpu_to_le16(EXT4_FC_TAG_INODE);
tl.fc_len = cpu_to_le16(inode_len + sizeof(fc_inode.fc_ino));
ret = -ECANCELED;
dst = ext4_fc_reserve_space(inode->i_sb,
EXT4_FC_TAG_BASE_LEN + inode_len + sizeof(fc_inode.fc_ino), crc);
if (!dst)
goto err;
if (!ext4_fc_memcpy(inode->i_sb, dst, &tl, EXT4_FC_TAG_BASE_LEN, crc))
goto err;
dst += EXT4_FC_TAG_BASE_LEN;
if (!ext4_fc_memcpy(inode->i_sb, dst, &fc_inode, sizeof(fc_inode), crc))
goto err;
dst += sizeof(fc_inode);
if (!ext4_fc_memcpy(inode->i_sb, dst, (u8 *)ext4_raw_inode(&iloc),
inode_len, crc))
goto err;
ret = 0;
err:
brelse(iloc.bh);
return ret;
}
/*
* Writes updated data ranges for the inode in question. Updates CRC.
* Returns 0 on success, error otherwise.
*/
static int ext4_fc_write_inode_data(struct inode *inode, u32 *crc)
{
ext4_lblk_t old_blk_size, cur_lblk_off, new_blk_size;
struct ext4_inode_info *ei = EXT4_I(inode);
struct ext4_map_blocks map;
struct ext4_fc_add_range fc_ext;
struct ext4_fc_del_range lrange;
struct ext4_extent *ex;
int ret;
mutex_lock(&ei->i_fc_lock);
if (ei->i_fc_lblk_len == 0) {
mutex_unlock(&ei->i_fc_lock);
return 0;
}
old_blk_size = ei->i_fc_lblk_start;
new_blk_size = ei->i_fc_lblk_start + ei->i_fc_lblk_len - 1;
ei->i_fc_lblk_len = 0;
mutex_unlock(&ei->i_fc_lock);
cur_lblk_off = old_blk_size;
ext4_debug("will try writing %d to %d for inode %ld\n",
cur_lblk_off, new_blk_size, inode->i_ino);
while (cur_lblk_off <= new_blk_size) {
map.m_lblk = cur_lblk_off;
map.m_len = new_blk_size - cur_lblk_off + 1;
ret = ext4_map_blocks(NULL, inode, &map, 0);
if (ret < 0)
return -ECANCELED;
if (map.m_len == 0) {
cur_lblk_off++;
continue;
}
if (ret == 0) {
lrange.fc_ino = cpu_to_le32(inode->i_ino);
lrange.fc_lblk = cpu_to_le32(map.m_lblk);
lrange.fc_len = cpu_to_le32(map.m_len);
if (!ext4_fc_add_tlv(inode->i_sb, EXT4_FC_TAG_DEL_RANGE,
sizeof(lrange), (u8 *)&lrange, crc))
return -ENOSPC;
} else {
unsigned int max = (map.m_flags & EXT4_MAP_UNWRITTEN) ?
EXT_UNWRITTEN_MAX_LEN : EXT_INIT_MAX_LEN;
/* Limit the number of blocks in one extent */
map.m_len = min(max, map.m_len);
fc_ext.fc_ino = cpu_to_le32(inode->i_ino);
ex = (struct ext4_extent *)&fc_ext.fc_ex;
ex->ee_block = cpu_to_le32(map.m_lblk);
ex->ee_len = cpu_to_le16(map.m_len);
ext4_ext_store_pblock(ex, map.m_pblk);
if (map.m_flags & EXT4_MAP_UNWRITTEN)
ext4_ext_mark_unwritten(ex);
else
ext4_ext_mark_initialized(ex);
if (!ext4_fc_add_tlv(inode->i_sb, EXT4_FC_TAG_ADD_RANGE,
sizeof(fc_ext), (u8 *)&fc_ext, crc))
return -ENOSPC;
}
cur_lblk_off += map.m_len;
}
return 0;
}
/* Submit data for all the fast commit inodes */
static int ext4_fc_submit_inode_data_all(journal_t *journal)
{
struct super_block *sb = journal->j_private;
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct ext4_inode_info *ei;
int ret = 0;
spin_lock(&sbi->s_fc_lock);
list_for_each_entry(ei, &sbi->s_fc_q[FC_Q_MAIN], i_fc_list) {
ext4_set_inode_state(&ei->vfs_inode, EXT4_STATE_FC_COMMITTING);
while (atomic_read(&ei->i_fc_updates)) {
DEFINE_WAIT(wait);
prepare_to_wait(&ei->i_fc_wait, &wait,
TASK_UNINTERRUPTIBLE);
if (atomic_read(&ei->i_fc_updates)) {
spin_unlock(&sbi->s_fc_lock);
schedule();
spin_lock(&sbi->s_fc_lock);
}
finish_wait(&ei->i_fc_wait, &wait);
}
spin_unlock(&sbi->s_fc_lock);
ret = jbd2_submit_inode_data(ei->jinode);
if (ret)
return ret;
spin_lock(&sbi->s_fc_lock);