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ext4: for committing inode, make ext4_fc_track_inode wait

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If the inode that's being requested to track using ext4_fc_track_inode
is being committed, then wait until the inode finishes the
commit. Also, add calls to ext4_fc_track_inode at the right places.
With this patch, now calling ext4_reserve_inode_write() results in
inode being tracked for next fast commit. This ensures that by the
time ext4_reserve_inode_write() returns, it is ready to be modified
and won't be committed until the corresponding handle is open.

A subtle lock ordering requirement with i_data_sem (which is
documented in the code) requires that ext4_fc_track_inode() be called
before grabbing i_data_sem. So, this patch also adds explicit
ext4_fc_track_inode() calls in places where i_data_sem grabbed.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://patch.msgid.link/20250508175908.1004880-3-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Harshad Shirwadkar
2025-05-08 17:59:01 +00:00
committed by Theodore Ts'o
parent 834224e81c
commit 4d3266463e
3 changed files with 41 additions and 0 deletions
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35
fs/ext4/fast_commit.c
View File

@@ -12,6 +12,7 @@
#include "ext4_extents.h"
#include "mballoc.h"
#include <linux/lockdep.h>
/*
* Ext4 Fast Commits
* -----------------
@@ -570,6 +571,8 @@ static int __track_inode(handle_t *handle, struct inode *inode, void *arg,
void ext4_fc_track_inode(handle_t *handle, struct inode *inode)
{
struct ext4_inode_info *ei = EXT4_I(inode);
wait_queue_head_t *wq;
int ret;
if (S_ISDIR(inode->i_mode))
@@ -587,6 +590,38 @@ void ext4_fc_track_inode(handle_t *handle, struct inode *inode)
if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FC_INELIGIBLE))
return;
if (!list_empty(&ei->i_fc_list))
return;
/*
* If we come here, we may sleep while waiting for the inode to
* commit. We shouldn't be holding i_data_sem when we go to sleep since
* the commit path needs to grab the lock while committing the inode.
*/
lockdep_assert_not_held(&ei->i_data_sem);
while (ext4_test_inode_state(inode, EXT4_STATE_FC_COMMITTING)) {
#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
prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
if (ext4_test_inode_state(inode, EXT4_STATE_FC_COMMITTING))
schedule();
finish_wait(wq, &wait.wq_entry);
}
/*
* From this point on, this inode will not be committed either
* by fast or full commit as long as the handle is open.
*/
ret = ext4_fc_track_template(handle, inode, __track_inode, NULL, 1);
trace_ext4_fc_track_inode(handle, inode, ret);
}