From: Jinke Han <[email protected]>
When disable and enable dioread_nolock by remount, we may see
dioread_lock in ext4_do_writepages while see dioread_nolock in
mpage_map_one_extent. This inconsistency may triger the warning
in ext4_add_complete_io when the io_end->handle is NULL. Although
this warning is harmless in most cases, there is still a risk of
insufficient log reservation in conversion of unwritten extents.
Signed-off-by: Jinke Han <[email protected]>
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/inode.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 40579ef513b7..122a22ccddb3 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1568,6 +1568,7 @@ struct mpage_da_data {
struct ext4_io_submit io_submit; /* IO submission data */
unsigned int do_map:1;
unsigned int scanned_until_end:1;
+ unsigned int dioread_nolock:1;
};
static void mpage_release_unused_pages(struct mpage_da_data *mpd,
@@ -2391,7 +2392,7 @@ static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
struct inode *inode = mpd->inode;
struct ext4_map_blocks *map = &mpd->map;
int get_blocks_flags;
- int err, dioread_nolock;
+ int err, dioread_nolock = mpd->dioread_nolock;
trace_ext4_da_write_pages_extent(inode, map);
/*
@@ -2412,7 +2413,6 @@ static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
EXT4_GET_BLOCKS_METADATA_NOFAIL |
EXT4_GET_BLOCKS_IO_SUBMIT;
- dioread_nolock = ext4_should_dioread_nolock(inode);
if (dioread_nolock)
get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
if (map->m_flags & BIT(BH_Delay))
@@ -2727,10 +2727,11 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
handle_t *handle = NULL;
struct inode *inode = mpd->inode;
struct address_space *mapping = inode->i_mapping;
- int needed_blocks, rsv_blocks = 0, ret = 0;
+ int needed_blocks, rsv_blocks = 0, rsv = 0, ret = 0;
struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
struct blk_plug plug;
bool give_up_on_write = false;
+ bool dioread_nolock;
trace_ext4_writepages(inode, wbc);
@@ -2783,15 +2784,6 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
ext4_journal_stop(handle);
}
- if (ext4_should_dioread_nolock(inode)) {
- /*
- * We may need to convert up to one extent per block in
- * the page and we may dirty the inode.
- */
- rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,
- PAGE_SIZE >> inode->i_blkbits);
- }
-
if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
range_whole = 1;
@@ -2837,6 +2829,18 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
goto unplug;
while (!mpd->scanned_until_end && wbc->nr_to_write > 0) {
+ dioread_nolock = ext4_should_dioread_nolock(inode);
+ if (!rsv && dioread_nolock) {
+ /*
+ * We may need to convert up to one extent per block in
+ * the page and we may dirty the inode.
+ */
+ rsv = 1 + ext4_chunk_trans_blocks(inode,
+ PAGE_SIZE >> inode->i_blkbits);
+ }
+ rsv_blocks = dioread_nolock ? rsv : 0;
+ mpd->dioread_nolock = dioread_nolock;
+
/* For each extent of pages we use new io_end */
mpd->io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
if (!mpd->io_submit.io_end) {
--
2.20.1
Jinke Han <[email protected]> writes:
> From: Jinke Han <[email protected]>
>
> When disable and enable dioread_nolock by remount, we may see
> dioread_lock in ext4_do_writepages while see dioread_nolock in
> mpage_map_one_extent. This inconsistency may triger the warning
> in ext4_add_complete_io when the io_end->handle is NULL. Although
> this warning is harmless in most cases, there is still a risk of
> insufficient log reservation in conversion of unwritten extents.
>
Sorry, I haven't completely gone through the patch yet. But this idea of
caching the initial value of mount parameter and passing it do different
functions while an I/O request completes, is not looking right to me.
If that's the case shouldn't we disallow this mount option to change
until all the outstanding I/O's are done or complete?
Then we need not cache the value of dioread_nolock at the start of
writepages and continue to pass it down in case it it changes.
Just my initial thoughts.
-ritesh
> Signed-off-by: Jinke Han <[email protected]>
> Signed-off-by: Zhang Yi <[email protected]>
> ---
> fs/ext4/inode.c | 28 ++++++++++++++++------------
> 1 file changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 40579ef513b7..122a22ccddb3 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1568,6 +1568,7 @@ struct mpage_da_data {
> struct ext4_io_submit io_submit; /* IO submission data */
> unsigned int do_map:1;
> unsigned int scanned_until_end:1;
> + unsigned int dioread_nolock:1;
> };
>
> static void mpage_release_unused_pages(struct mpage_da_data *mpd,
> @@ -2391,7 +2392,7 @@ static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
> struct inode *inode = mpd->inode;
> struct ext4_map_blocks *map = &mpd->map;
> int get_blocks_flags;
> - int err, dioread_nolock;
> + int err, dioread_nolock = mpd->dioread_nolock;
>
> trace_ext4_da_write_pages_extent(inode, map);
> /*
> @@ -2412,7 +2413,6 @@ static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
> get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
> EXT4_GET_BLOCKS_METADATA_NOFAIL |
> EXT4_GET_BLOCKS_IO_SUBMIT;
> - dioread_nolock = ext4_should_dioread_nolock(inode);
> if (dioread_nolock)
> get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
> if (map->m_flags & BIT(BH_Delay))
> @@ -2727,10 +2727,11 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
> handle_t *handle = NULL;
> struct inode *inode = mpd->inode;
> struct address_space *mapping = inode->i_mapping;
> - int needed_blocks, rsv_blocks = 0, ret = 0;
> + int needed_blocks, rsv_blocks = 0, rsv = 0, ret = 0;
> struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
> struct blk_plug plug;
> bool give_up_on_write = false;
> + bool dioread_nolock;
>
> trace_ext4_writepages(inode, wbc);
>
> @@ -2783,15 +2784,6 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
> ext4_journal_stop(handle);
> }
>
> - if (ext4_should_dioread_nolock(inode)) {
> - /*
> - * We may need to convert up to one extent per block in
> - * the page and we may dirty the inode.
> - */
> - rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,
> - PAGE_SIZE >> inode->i_blkbits);
> - }
> -
> if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
> range_whole = 1;
>
> @@ -2837,6 +2829,18 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
> goto unplug;
>
> while (!mpd->scanned_until_end && wbc->nr_to_write > 0) {
> + dioread_nolock = ext4_should_dioread_nolock(inode);
> + if (!rsv && dioread_nolock) {
> + /*
> + * We may need to convert up to one extent per block in
> + * the page and we may dirty the inode.
> + */
> + rsv = 1 + ext4_chunk_trans_blocks(inode,
> + PAGE_SIZE >> inode->i_blkbits);
> + }
> + rsv_blocks = dioread_nolock ? rsv : 0;
> + mpd->dioread_nolock = dioread_nolock;
> +
> /* For each extent of pages we use new io_end */
> mpd->io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
> if (!mpd->io_submit.io_end) {
> --
> 2.20.1
在 2023/2/16 下午9:13, Ritesh Harjani (IBM) 写道:
> Jinke Han <[email protected]> writes:
>
>> From: Jinke Han <[email protected]>
>>
>> When disable and enable dioread_nolock by remount, we may see
>> dioread_lock in ext4_do_writepages while see dioread_nolock in
>> mpage_map_one_extent. This inconsistency may triger the warning
>> in ext4_add_complete_io when the io_end->handle is NULL. Although
>> this warning is harmless in most cases, there is still a risk of
>> insufficient log reservation in conversion of unwritten extents.
>>
>
> Sorry, I haven't completely gone through the patch yet. But this idea of
> caching the initial value of mount parameter and passing it do different
> functions while an I/O request completes, is not looking right to me.
>
> If that's the case shouldn't we disallow this mount option to change
> until all the outstanding I/O's are done or complete?
> Then we need not cache the value of dioread_nolock at the start of
> writepages and continue to pass it down in case it it changes.
>
> Just my initial thoughts.
>
> -ritesh
>
Fair enough, thanks.