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jbd2: store jinode dirty range in PAGE_SIZE units

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jbd2_inode fields are updated under journal->j_list_lock, but some paths
read them without holding the lock (e.g. fast commit helpers and ordered
truncate helpers).

READ_ONCE() alone is not sufficient for the dirty range fields when they
are stored as loff_t because 32-bit platforms can observe torn loads.
Store the dirty range in PAGE_SIZE units as pgoff_t instead.

Represent the dirty range end as an exclusive end page. This avoids a
special sentinel value and keeps MAX_LFS_FILESIZE on 32-bit representable.

Publish a new dirty range by updating end_page before start_page, and
treat start_page >= end_page as empty in the accessor for robustness.

Use READ_ONCE() on the read side and WRITE_ONCE() on the write side for the
dirty range and i_flags to match the existing lockless access pattern.

Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Li Chen <me@linux.beauty>
Link: https://patch.msgid.link/20260306085643.465275-5-me@linux.beauty
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Li Chen
2026-03-06 16:56:42 +08:00
committed by Theodore Ts'o
parent be81084e03
commit 4edafa81a1
4 changed files with 81 additions and 36 deletions
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55
fs/jbd2/commit.c
View File

@@ -180,7 +180,13 @@ static int journal_wait_on_commit_record(journal_t *journal,
/* Send all the data buffers related to an inode */
int jbd2_submit_inode_data(journal_t *journal, struct jbd2_inode *jinode)
{
if (!jinode || !(jinode->i_flags & JI_WRITE_DATA))
unsigned long flags;
if (!jinode)
return 0;
flags = READ_ONCE(jinode->i_flags);
if (!(flags & JI_WRITE_DATA))
return 0;
trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
@@ -191,12 +197,30 @@ EXPORT_SYMBOL(jbd2_submit_inode_data);
int jbd2_wait_inode_data(journal_t *journal, struct jbd2_inode *jinode)
{
if (!jinode || !(jinode->i_flags & JI_WAIT_DATA) ||
!jinode->i_vfs_inode || !jinode->i_vfs_inode->i_mapping)
struct address_space *mapping;
struct inode *inode;
unsigned long flags;
loff_t start_byte, end_byte;
if (!jinode)
return 0;
flags = READ_ONCE(jinode->i_flags);
if (!(flags & JI_WAIT_DATA))
return 0;
inode = jinode->i_vfs_inode;
if (!inode)
return 0;
mapping = inode->i_mapping;
if (!mapping)
return 0;
if (!jbd2_jinode_get_dirty_range(jinode, &start_byte, &end_byte))
return 0;
return filemap_fdatawait_range_keep_errors(
jinode->i_vfs_inode->i_mapping, jinode->i_dirty_start,
jinode->i_dirty_end);
mapping, start_byte, end_byte);
}
EXPORT_SYMBOL(jbd2_wait_inode_data);
@@ -218,7 +242,8 @@ static int journal_submit_data_buffers(journal_t *journal,
list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
if (!(jinode->i_flags & JI_WRITE_DATA))
continue;
jinode->i_flags |= JI_COMMIT_RUNNING;
WRITE_ONCE(jinode->i_flags,
jinode->i_flags | JI_COMMIT_RUNNING);
spin_unlock(&journal->j_list_lock);
/* submit the inode data buffers. */
trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
@@ -229,7 +254,8 @@ static int journal_submit_data_buffers(journal_t *journal,
}
spin_lock(&journal->j_list_lock);
J_ASSERT(jinode->i_transaction == commit_transaction);
jinode->i_flags &= ~JI_COMMIT_RUNNING;
WRITE_ONCE(jinode->i_flags,
jinode->i_flags & ~JI_COMMIT_RUNNING);
smp_mb();
wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
}
@@ -240,10 +266,13 @@ static int journal_submit_data_buffers(journal_t *journal,
int jbd2_journal_finish_inode_data_buffers(struct jbd2_inode *jinode)
{
struct address_space *mapping = jinode->i_vfs_inode->i_mapping;
loff_t start_byte, end_byte;
if (!jbd2_jinode_get_dirty_range(jinode, &start_byte, &end_byte))
return 0;
return filemap_fdatawait_range_keep_errors(mapping,
jinode->i_dirty_start,
jinode->i_dirty_end);
start_byte, end_byte);
}
/*
@@ -262,7 +291,7 @@ static int journal_finish_inode_data_buffers(journal_t *journal,
list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
if (!(jinode->i_flags & JI_WAIT_DATA))
continue;
jinode->i_flags |= JI_COMMIT_RUNNING;
WRITE_ONCE(jinode->i_flags, jinode->i_flags | JI_COMMIT_RUNNING);
spin_unlock(&journal->j_list_lock);
/* wait for the inode data buffers writeout. */
if (journal->j_finish_inode_data_buffers) {
@@ -272,7 +301,7 @@ static int journal_finish_inode_data_buffers(journal_t *journal,
}
cond_resched();
spin_lock(&journal->j_list_lock);
jinode->i_flags &= ~JI_COMMIT_RUNNING;
WRITE_ONCE(jinode->i_flags, jinode->i_flags & ~JI_COMMIT_RUNNING);
smp_mb();
wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
}
@@ -288,8 +317,8 @@ static int journal_finish_inode_data_buffers(journal_t *journal,
&jinode->i_transaction->t_inode_list);
} else {
jinode->i_transaction = NULL;
jinode->i_dirty_start = 0;
jinode->i_dirty_end = 0;
WRITE_ONCE(jinode->i_dirty_start_page, 0);
WRITE_ONCE(jinode->i_dirty_end_page, 0);
}
}
spin_unlock(&journal->j_list_lock);