On 2025/7/7 22:08, Zhang Yi wrote: > From: Zhang Yi <yi.zhang@xxxxxxxxxx> > > In environments with a page size of 64KB, the maximum size of a folio > can reach up to 128MB. Consequently, during the write-back of folios, > the 'rsv_blocks' will be overestimated to 1,577, which can make > pressure on the journal space where the journal is small. This can > easily exceed the limit of a single transaction. Besides, an excessively > large folio is meaningless and will instead increase the overhead of > traversing the bhs within the folio. Therefore, limit the maximum order > of a folio to 2048 filesystem blocks. > > Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> > Reported-by: Joseph Qi <jiangqi903@xxxxxxxxx> > Closes: https://lore.kernel.org/linux-ext4/CA+G9fYsyYQ3ZL4xaSg1-Tt5Evto7Zd+hgNWZEa9cQLbahA1+xg@xxxxxxxxxxxxxx/ > Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx> Confirmed that this can fix the following jbd2 warning in start_this_handle(): "JBD2: kworker/u32:0 wants too many credits credits:32 rsv_credits:1577 max:2695" Tested-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> > --- > fs/ext4/ext4.h | 2 +- > fs/ext4/ialloc.c | 3 +-- > fs/ext4/inode.c | 22 +++++++++++++++++++--- > 3 files changed, 21 insertions(+), 6 deletions(-) > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h > index f705046ba6c6..9ac0a7d4fa0c 100644 > --- a/fs/ext4/ext4.h > +++ b/fs/ext4/ext4.h > @@ -3020,7 +3020,7 @@ int ext4_walk_page_buffers(handle_t *handle, > struct buffer_head *bh)); > int do_journal_get_write_access(handle_t *handle, struct inode *inode, > struct buffer_head *bh); > -bool ext4_should_enable_large_folio(struct inode *inode); > +void ext4_set_inode_mapping_order(struct inode *inode); > #define FALL_BACK_TO_NONDELALLOC 1 > #define CONVERT_INLINE_DATA 2 > > diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c > index 79aa3df8d019..df4051613b29 100644 > --- a/fs/ext4/ialloc.c > +++ b/fs/ext4/ialloc.c > @@ -1335,8 +1335,7 @@ struct inode *__ext4_new_inode(struct mnt_idmap *idmap, > } > } > > - if (ext4_should_enable_large_folio(inode)) > - mapping_set_large_folios(inode->i_mapping); > + ext4_set_inode_mapping_order(inode); > > ext4_update_inode_fsync_trans(handle, inode, 1); > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 4b679cb6c8bd..1bce9ebaedb7 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -5181,7 +5181,7 @@ static int check_igot_inode(struct inode *inode, ext4_iget_flags flags, > return -EFSCORRUPTED; > } > > -bool ext4_should_enable_large_folio(struct inode *inode) > +static bool ext4_should_enable_large_folio(struct inode *inode) > { > struct super_block *sb = inode->i_sb; > > @@ -5198,6 +5198,22 @@ bool ext4_should_enable_large_folio(struct inode *inode) > return true; > } > > +/* > + * Limit the maximum folio order to 2048 blocks to prevent overestimation > + * of reserve handle credits during the folio writeback in environments > + * where the PAGE_SIZE exceeds 4KB. > + */ > +#define EXT4_MAX_PAGECACHE_ORDER(i) \ > + min(MAX_PAGECACHE_ORDER, (11 + (i)->i_blkbits - PAGE_SHIFT)) > +void ext4_set_inode_mapping_order(struct inode *inode) > +{ > + if (!ext4_should_enable_large_folio(inode)) > + return; > + > + mapping_set_folio_order_range(inode->i_mapping, 0, > + EXT4_MAX_PAGECACHE_ORDER(inode)); > +} > + > struct inode *__ext4_iget(struct super_block *sb, unsigned long ino, > ext4_iget_flags flags, const char *function, > unsigned int line) > @@ -5515,8 +5531,8 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino, > ret = -EFSCORRUPTED; > goto bad_inode; > } > - if (ext4_should_enable_large_folio(inode)) > - mapping_set_large_folios(inode->i_mapping); > + > + ext4_set_inode_mapping_order(inode); > > ret = check_igot_inode(inode, flags, function, line); > /*
