| Message ID | 53596bdf7bd7aed66020db98d903b1653a1dbc7a.1644062450.git.riteshh@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ext4: fast_commit fixes, stricter block checking & cleanups | expand |
On Sat 05-02-22 19:39:51, Ritesh Harjani wrote: > In case of flex_bg feature (which is by default enabled), extents for > any given inode might span across blocks from two different block group. > ext4_mb_mark_bb() only reads the buffer_head of block bitmap once for the > starting block group, but it fails to read it again when the extent length > boundary overflows to another block group. Then in this below loop it > accesses memory beyond the block group bitmap buffer_head and results > into a data abort. > > for (i = 0; i < clen; i++) > if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) > already++; > > This patch adds this functionality for checking block group boundary in > ext4_mb_mark_bb() and update the buffer_head(bitmap_bh) for every different > block group. > > w/o this patch, I was easily able to hit a data access abort using Power platform. > > <...> > [ 74.327662] EXT4-fs error (device loop3): ext4_mb_generate_buddy:1141: group 11, block bitmap and bg descriptor inconsistent: 21248 vs 23294 free clusters > [ 74.533214] EXT4-fs (loop3): shut down requested (2) > [ 74.536705] Aborting journal on device loop3-8. > [ 74.702705] BUG: Unable to handle kernel data access on read at 0xc00000005e980000 > [ 74.703727] Faulting instruction address: 0xc0000000007bffb8 > cpu 0xd: Vector: 300 (Data Access) at [c000000015db7060] > pc: c0000000007bffb8: ext4_mb_mark_bb+0x198/0x5a0 > lr: c0000000007bfeec: ext4_mb_mark_bb+0xcc/0x5a0 > sp: c000000015db7300 > msr: 800000000280b033 > dar: c00000005e980000 > dsisr: 40000000 > current = 0xc000000027af6880 > paca = 0xc00000003ffd5200 irqmask: 0x03 irq_happened: 0x01 > pid = 5167, comm = mount > <...> > enter ? for help > [c000000015db7380] c000000000782708 ext4_ext_clear_bb+0x378/0x410 > [c000000015db7400] c000000000813f14 ext4_fc_replay+0x1794/0x2000 > [c000000015db7580] c000000000833f7c do_one_pass+0xe9c/0x12a0 > [c000000015db7710] c000000000834504 jbd2_journal_recover+0x184/0x2d0 > [c000000015db77c0] c000000000841398 jbd2_journal_load+0x188/0x4a0 > [c000000015db7880] c000000000804de8 ext4_fill_super+0x2638/0x3e10 > [c000000015db7a40] c0000000005f8404 get_tree_bdev+0x2b4/0x350 > [c000000015db7ae0] c0000000007ef058 ext4_get_tree+0x28/0x40 > [c000000015db7b00] c0000000005f6344 vfs_get_tree+0x44/0x100 > [c000000015db7b70] c00000000063c408 path_mount+0xdd8/0xe70 > [c000000015db7c40] c00000000063c8f0 sys_mount+0x450/0x550 > [c000000015db7d50] c000000000035770 system_call_exception+0x4a0/0x4e0 > [c000000015db7e10] c00000000000c74c system_call_common+0xec/0x250 > > Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com> Just two nits below. Otherwise feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> > --- > fs/ext4/mballoc.c | 131 +++++++++++++++++++++++++++------------------- > 1 file changed, 76 insertions(+), 55 deletions(-) > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > index 2f117ce3bb73..d0bd51b1e1ad 100644 > --- a/fs/ext4/mballoc.c > +++ b/fs/ext4/mballoc.c > @@ -3901,72 +3901,93 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block, > ext4_grpblk_t blkoff; > int i, err; > int already; > - unsigned int clen, clen_changed; > + unsigned int clen, clen_changed, thisgrp_len; > > - clen = EXT4_NUM_B2C(sbi, len); > - > - ext4_get_group_no_and_offset(sb, block, &group, &blkoff); > - bitmap_bh = ext4_read_block_bitmap(sb, group); > - if (IS_ERR(bitmap_bh)) { > - err = PTR_ERR(bitmap_bh); > - bitmap_bh = NULL; > - goto out_err; > - } > - > - err = -EIO; > - gdp = ext4_get_group_desc(sb, group, &gdp_bh); > - if (!gdp) > - goto out_err; > + while (len > 0) { > + ext4_get_group_no_and_offset(sb, block, &group, &blkoff); > > - ext4_lock_group(sb, group); > - already = 0; > - for (i = 0; i < clen; i++) > - if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) > - already++; > - > - clen_changed = clen - already; > - if (state) > - ext4_set_bits(bitmap_bh->b_data, blkoff, clen); > - else > - mb_test_and_clear_bits(bitmap_bh->b_data, blkoff, clen); > - if (ext4_has_group_desc_csum(sb) && > - (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { > - gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT); > - ext4_free_group_clusters_set(sb, gdp, > - ext4_free_clusters_after_init(sb, > - group, gdp)); > - } > - if (state) > - clen = ext4_free_group_clusters(sb, gdp) - clen_changed; > - else > - clen = ext4_free_group_clusters(sb, gdp) + clen_changed; > + /* > + * Check to see if we are freeing blocks across a group > + * boundary. > + * In case of flex_bg, this can happen that (block, len) may > + * span across more than one group. In that case we need to > + * get the corresponding group metadata to work with. > + * For this we have goto again loop. > + */ > + thisgrp_len = min_t(unsigned int, (unsigned int)len, > + EXT4_BLOCKS_PER_GROUP(sb) - EXT4_C2B(sbi, blkoff)); > + clen = EXT4_NUM_B2C(sbi, thisgrp_len); > > - ext4_free_group_clusters_set(sb, gdp, clen); > - ext4_block_bitmap_csum_set(sb, group, gdp, bitmap_bh); > - ext4_group_desc_csum_set(sb, group, gdp); > + bitmap_bh = ext4_read_block_bitmap(sb, group); > + if (IS_ERR(bitmap_bh)) { > + err = PTR_ERR(bitmap_bh); > + bitmap_bh = NULL; > + break; > + } > > - ext4_unlock_group(sb, group); > + err = -EIO; > + gdp = ext4_get_group_desc(sb, group, &gdp_bh); > + if (!gdp) > + break; > > - if (sbi->s_log_groups_per_flex) { > - ext4_group_t flex_group = ext4_flex_group(sbi, group); > - struct flex_groups *fg = sbi_array_rcu_deref(sbi, > - s_flex_groups, flex_group); > + ext4_lock_group(sb, group); > + already = 0; > + for (i = 0; i < clen; i++) > + if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == > + !state) > + already++; > > + clen_changed = clen - already; > if (state) > - atomic64_sub(clen_changed, &fg->free_clusters); > + ext4_set_bits(bitmap_bh->b_data, blkoff, clen); > else > - atomic64_add(clen_changed, &fg->free_clusters); > + mb_test_and_clear_bits(bitmap_bh->b_data, blkoff, clen); > + if (ext4_has_group_desc_csum(sb) && > + (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { > + gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT); > + ext4_free_group_clusters_set(sb, gdp, > + ext4_free_clusters_after_init(sb, group, gdp)); > + } > + if (state) > + clen = ext4_free_group_clusters(sb, gdp) - clen_changed; > + else > + clen = ext4_free_group_clusters(sb, gdp) + clen_changed; > + > + ext4_free_group_clusters_set(sb, gdp, clen); > + ext4_block_bitmap_csum_set(sb, group, gdp, bitmap_bh); > + ext4_group_desc_csum_set(sb, group, gdp); > + > + ext4_unlock_group(sb, group); > + > + if (sbi->s_log_groups_per_flex) { > + ext4_group_t flex_group = ext4_flex_group(sbi, group); > + struct flex_groups *fg = sbi_array_rcu_deref(sbi, > + s_flex_groups, flex_group); > + > + if (state) > + atomic64_sub(clen_changed, &fg->free_clusters); > + else > + atomic64_add(clen_changed, &fg->free_clusters); > + > + } > + > + err = ext4_handle_dirty_metadata(NULL, NULL, bitmap_bh); > + if (err) > + break; > + sync_dirty_buffer(bitmap_bh); > + err = ext4_handle_dirty_metadata(NULL, NULL, gdp_bh); > + sync_dirty_buffer(gdp_bh); > + if (err) > + break; > + > + block += thisgrp_len; > + len = len - thisgrp_len; ^^^ Maybe: len -= thisgrp_len; > + put_bh(bitmap_bh); ^^ brelse() would be more usual here... Honza
On 22/02/07 05:37PM, Jan Kara wrote: > On Sat 05-02-22 19:39:51, Ritesh Harjani wrote: > > In case of flex_bg feature (which is by default enabled), extents for > > any given inode might span across blocks from two different block group. > > ext4_mb_mark_bb() only reads the buffer_head of block bitmap once for the > > starting block group, but it fails to read it again when the extent length > > boundary overflows to another block group. Then in this below loop it > > accesses memory beyond the block group bitmap buffer_head and results > > into a data abort. > > > > for (i = 0; i < clen; i++) > > if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) > > already++; > > > > This patch adds this functionality for checking block group boundary in > > ext4_mb_mark_bb() and update the buffer_head(bitmap_bh) for every different > > block group. > > > > w/o this patch, I was easily able to hit a data access abort using Power platform. > > > > <...> > > [ 74.327662] EXT4-fs error (device loop3): ext4_mb_generate_buddy:1141: group 11, block bitmap and bg descriptor inconsistent: 21248 vs 23294 free clusters > > [ 74.533214] EXT4-fs (loop3): shut down requested (2) > > [ 74.536705] Aborting journal on device loop3-8. > > [ 74.702705] BUG: Unable to handle kernel data access on read at 0xc00000005e980000 > > [ 74.703727] Faulting instruction address: 0xc0000000007bffb8 > > cpu 0xd: Vector: 300 (Data Access) at [c000000015db7060] > > pc: c0000000007bffb8: ext4_mb_mark_bb+0x198/0x5a0 > > lr: c0000000007bfeec: ext4_mb_mark_bb+0xcc/0x5a0 > > sp: c000000015db7300 > > msr: 800000000280b033 > > dar: c00000005e980000 > > dsisr: 40000000 > > current = 0xc000000027af6880 > > paca = 0xc00000003ffd5200 irqmask: 0x03 irq_happened: 0x01 > > pid = 5167, comm = mount > > <...> > > enter ? for help > > [c000000015db7380] c000000000782708 ext4_ext_clear_bb+0x378/0x410 > > [c000000015db7400] c000000000813f14 ext4_fc_replay+0x1794/0x2000 > > [c000000015db7580] c000000000833f7c do_one_pass+0xe9c/0x12a0 > > [c000000015db7710] c000000000834504 jbd2_journal_recover+0x184/0x2d0 > > [c000000015db77c0] c000000000841398 jbd2_journal_load+0x188/0x4a0 > > [c000000015db7880] c000000000804de8 ext4_fill_super+0x2638/0x3e10 > > [c000000015db7a40] c0000000005f8404 get_tree_bdev+0x2b4/0x350 > > [c000000015db7ae0] c0000000007ef058 ext4_get_tree+0x28/0x40 > > [c000000015db7b00] c0000000005f6344 vfs_get_tree+0x44/0x100 > > [c000000015db7b70] c00000000063c408 path_mount+0xdd8/0xe70 > > [c000000015db7c40] c00000000063c8f0 sys_mount+0x450/0x550 > > [c000000015db7d50] c000000000035770 system_call_exception+0x4a0/0x4e0 > > [c000000015db7e10] c00000000000c74c system_call_common+0xec/0x250 > > > > Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com> > > Just two nits below. Otherwise feel free to add: > > Reviewed-by: Jan Kara <jack@suse.cz> > > > --- > > fs/ext4/mballoc.c | 131 +++++++++++++++++++++++++++------------------- > > 1 file changed, 76 insertions(+), 55 deletions(-) > > > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > > index 2f117ce3bb73..d0bd51b1e1ad 100644 > > --- a/fs/ext4/mballoc.c > > +++ b/fs/ext4/mballoc.c > > @@ -3901,72 +3901,93 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block, > > ext4_grpblk_t blkoff; > > int i, err; > > int already; > > - unsigned int clen, clen_changed; > > + unsigned int clen, clen_changed, thisgrp_len; > > > > - clen = EXT4_NUM_B2C(sbi, len); > > - > > - ext4_get_group_no_and_offset(sb, block, &group, &blkoff); > > - bitmap_bh = ext4_read_block_bitmap(sb, group); > > - if (IS_ERR(bitmap_bh)) { > > - err = PTR_ERR(bitmap_bh); > > - bitmap_bh = NULL; > > - goto out_err; > > - } > > - > > - err = -EIO; > > - gdp = ext4_get_group_desc(sb, group, &gdp_bh); > > - if (!gdp) > > - goto out_err; > > + while (len > 0) { > > + ext4_get_group_no_and_offset(sb, block, &group, &blkoff); > > > > - ext4_lock_group(sb, group); > > - already = 0; > > - for (i = 0; i < clen; i++) > > - if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) > > - already++; > > - > > - clen_changed = clen - already; > > - if (state) > > - ext4_set_bits(bitmap_bh->b_data, blkoff, clen); > > - else > > - mb_test_and_clear_bits(bitmap_bh->b_data, blkoff, clen); > > - if (ext4_has_group_desc_csum(sb) && > > - (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { > > - gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT); > > - ext4_free_group_clusters_set(sb, gdp, > > - ext4_free_clusters_after_init(sb, > > - group, gdp)); > > - } > > - if (state) > > - clen = ext4_free_group_clusters(sb, gdp) - clen_changed; > > - else > > - clen = ext4_free_group_clusters(sb, gdp) + clen_changed; > > + /* > > + * Check to see if we are freeing blocks across a group > > + * boundary. > > + * In case of flex_bg, this can happen that (block, len) may > > + * span across more than one group. In that case we need to > > + * get the corresponding group metadata to work with. > > + * For this we have goto again loop. > > + */ > > + thisgrp_len = min_t(unsigned int, (unsigned int)len, > > + EXT4_BLOCKS_PER_GROUP(sb) - EXT4_C2B(sbi, blkoff)); > > + clen = EXT4_NUM_B2C(sbi, thisgrp_len); > > > > - ext4_free_group_clusters_set(sb, gdp, clen); > > - ext4_block_bitmap_csum_set(sb, group, gdp, bitmap_bh); > > - ext4_group_desc_csum_set(sb, group, gdp); > > + bitmap_bh = ext4_read_block_bitmap(sb, group); > > + if (IS_ERR(bitmap_bh)) { > > + err = PTR_ERR(bitmap_bh); > > + bitmap_bh = NULL; > > + break; > > + } > > > > - ext4_unlock_group(sb, group); > > + err = -EIO; > > + gdp = ext4_get_group_desc(sb, group, &gdp_bh); > > + if (!gdp) > > + break; > > > > - if (sbi->s_log_groups_per_flex) { > > - ext4_group_t flex_group = ext4_flex_group(sbi, group); > > - struct flex_groups *fg = sbi_array_rcu_deref(sbi, > > - s_flex_groups, flex_group); > > + ext4_lock_group(sb, group); > > + already = 0; > > + for (i = 0; i < clen; i++) > > + if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == > > + !state) > > + already++; > > > > + clen_changed = clen - already; > > if (state) > > - atomic64_sub(clen_changed, &fg->free_clusters); > > + ext4_set_bits(bitmap_bh->b_data, blkoff, clen); > > else > > - atomic64_add(clen_changed, &fg->free_clusters); > > + mb_test_and_clear_bits(bitmap_bh->b_data, blkoff, clen); > > + if (ext4_has_group_desc_csum(sb) && > > + (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { > > + gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT); > > + ext4_free_group_clusters_set(sb, gdp, > > + ext4_free_clusters_after_init(sb, group, gdp)); > > + } > > + if (state) > > + clen = ext4_free_group_clusters(sb, gdp) - clen_changed; > > + else > > + clen = ext4_free_group_clusters(sb, gdp) + clen_changed; > > + > > + ext4_free_group_clusters_set(sb, gdp, clen); > > + ext4_block_bitmap_csum_set(sb, group, gdp, bitmap_bh); > > + ext4_group_desc_csum_set(sb, group, gdp); > > + > > + ext4_unlock_group(sb, group); > > + > > + if (sbi->s_log_groups_per_flex) { > > + ext4_group_t flex_group = ext4_flex_group(sbi, group); > > + struct flex_groups *fg = sbi_array_rcu_deref(sbi, > > + s_flex_groups, flex_group); > > + > > + if (state) > > + atomic64_sub(clen_changed, &fg->free_clusters); > > + else > > + atomic64_add(clen_changed, &fg->free_clusters); > > + > > + } > > + > > + err = ext4_handle_dirty_metadata(NULL, NULL, bitmap_bh); > > + if (err) > > + break; > > + sync_dirty_buffer(bitmap_bh); > > + err = ext4_handle_dirty_metadata(NULL, NULL, gdp_bh); > > + sync_dirty_buffer(gdp_bh); > > + if (err) > > + break; > > + > > + block += thisgrp_len; > > + len = len - thisgrp_len; > ^^^ Maybe: len -= thisgrp_len; > > > + put_bh(bitmap_bh); > ^^ brelse() would be more usual here... Sure, will make above two changes. Btw, any general rules of when should we use put_bh() v/s brelse()? Assumption about why I used put_bh() above was that in a non-error loop, where we are doing ext4_read_block_bitmap() (which will return bh with b_count elevated), I thought, we could simply do put_bh() in the end. But when there is a possibility of an error occurred somewhere in between, then it's safe to do brelse(). -ritesh > > > Honza > -- > Jan Kara <jack@suse.com> > SUSE Labs, CR
On Tue 08-02-22 08:41:07, Ritesh Harjani wrote: > On 22/02/07 05:37PM, Jan Kara wrote: > > On Sat 05-02-22 19:39:51, Ritesh Harjani wrote: > > > In case of flex_bg feature (which is by default enabled), extents for > > > any given inode might span across blocks from two different block group. > > > ext4_mb_mark_bb() only reads the buffer_head of block bitmap once for the > > > starting block group, but it fails to read it again when the extent length > > > boundary overflows to another block group. Then in this below loop it > > > accesses memory beyond the block group bitmap buffer_head and results > > > into a data abort. > > > > > > for (i = 0; i < clen; i++) > > > if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) > > > already++; > > > > > > This patch adds this functionality for checking block group boundary in > > > ext4_mb_mark_bb() and update the buffer_head(bitmap_bh) for every different > > > block group. > > > > > > w/o this patch, I was easily able to hit a data access abort using Power platform. > > > > > > <...> > > > [ 74.327662] EXT4-fs error (device loop3): ext4_mb_generate_buddy:1141: group 11, block bitmap and bg descriptor inconsistent: 21248 vs 23294 free clusters > > > [ 74.533214] EXT4-fs (loop3): shut down requested (2) > > > [ 74.536705] Aborting journal on device loop3-8. > > > [ 74.702705] BUG: Unable to handle kernel data access on read at 0xc00000005e980000 > > > [ 74.703727] Faulting instruction address: 0xc0000000007bffb8 > > > cpu 0xd: Vector: 300 (Data Access) at [c000000015db7060] > > > pc: c0000000007bffb8: ext4_mb_mark_bb+0x198/0x5a0 > > > lr: c0000000007bfeec: ext4_mb_mark_bb+0xcc/0x5a0 > > > sp: c000000015db7300 > > > msr: 800000000280b033 > > > dar: c00000005e980000 > > > dsisr: 40000000 > > > current = 0xc000000027af6880 > > > paca = 0xc00000003ffd5200 irqmask: 0x03 irq_happened: 0x01 > > > pid = 5167, comm = mount > > > <...> > > > enter ? for help > > > [c000000015db7380] c000000000782708 ext4_ext_clear_bb+0x378/0x410 > > > [c000000015db7400] c000000000813f14 ext4_fc_replay+0x1794/0x2000 > > > [c000000015db7580] c000000000833f7c do_one_pass+0xe9c/0x12a0 > > > [c000000015db7710] c000000000834504 jbd2_journal_recover+0x184/0x2d0 > > > [c000000015db77c0] c000000000841398 jbd2_journal_load+0x188/0x4a0 > > > [c000000015db7880] c000000000804de8 ext4_fill_super+0x2638/0x3e10 > > > [c000000015db7a40] c0000000005f8404 get_tree_bdev+0x2b4/0x350 > > > [c000000015db7ae0] c0000000007ef058 ext4_get_tree+0x28/0x40 > > > [c000000015db7b00] c0000000005f6344 vfs_get_tree+0x44/0x100 > > > [c000000015db7b70] c00000000063c408 path_mount+0xdd8/0xe70 > > > [c000000015db7c40] c00000000063c8f0 sys_mount+0x450/0x550 > > > [c000000015db7d50] c000000000035770 system_call_exception+0x4a0/0x4e0 > > > [c000000015db7e10] c00000000000c74c system_call_common+0xec/0x250 > > > > > > Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com> > > > > Just two nits below. Otherwise feel free to add: > > > > Reviewed-by: Jan Kara <jack@suse.cz> > > > > > --- > > > fs/ext4/mballoc.c | 131 +++++++++++++++++++++++++++------------------- > > > 1 file changed, 76 insertions(+), 55 deletions(-) > > > > > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > > > index 2f117ce3bb73..d0bd51b1e1ad 100644 > > > --- a/fs/ext4/mballoc.c > > > +++ b/fs/ext4/mballoc.c > > > @@ -3901,72 +3901,93 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block, > > > ext4_grpblk_t blkoff; > > > int i, err; > > > int already; > > > - unsigned int clen, clen_changed; > > > + unsigned int clen, clen_changed, thisgrp_len; > > > > > > - clen = EXT4_NUM_B2C(sbi, len); > > > - > > > - ext4_get_group_no_and_offset(sb, block, &group, &blkoff); > > > - bitmap_bh = ext4_read_block_bitmap(sb, group); > > > - if (IS_ERR(bitmap_bh)) { > > > - err = PTR_ERR(bitmap_bh); > > > - bitmap_bh = NULL; > > > - goto out_err; > > > - } > > > - > > > - err = -EIO; > > > - gdp = ext4_get_group_desc(sb, group, &gdp_bh); > > > - if (!gdp) > > > - goto out_err; > > > + while (len > 0) { > > > + ext4_get_group_no_and_offset(sb, block, &group, &blkoff); > > > > > > - ext4_lock_group(sb, group); > > > - already = 0; > > > - for (i = 0; i < clen; i++) > > > - if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) > > > - already++; > > > - > > > - clen_changed = clen - already; > > > - if (state) > > > - ext4_set_bits(bitmap_bh->b_data, blkoff, clen); > > > - else > > > - mb_test_and_clear_bits(bitmap_bh->b_data, blkoff, clen); > > > - if (ext4_has_group_desc_csum(sb) && > > > - (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { > > > - gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT); > > > - ext4_free_group_clusters_set(sb, gdp, > > > - ext4_free_clusters_after_init(sb, > > > - group, gdp)); > > > - } > > > - if (state) > > > - clen = ext4_free_group_clusters(sb, gdp) - clen_changed; > > > - else > > > - clen = ext4_free_group_clusters(sb, gdp) + clen_changed; > > > + /* > > > + * Check to see if we are freeing blocks across a group > > > + * boundary. > > > + * In case of flex_bg, this can happen that (block, len) may > > > + * span across more than one group. In that case we need to > > > + * get the corresponding group metadata to work with. > > > + * For this we have goto again loop. > > > + */ > > > + thisgrp_len = min_t(unsigned int, (unsigned int)len, > > > + EXT4_BLOCKS_PER_GROUP(sb) - EXT4_C2B(sbi, blkoff)); > > > + clen = EXT4_NUM_B2C(sbi, thisgrp_len); > > > > > > - ext4_free_group_clusters_set(sb, gdp, clen); > > > - ext4_block_bitmap_csum_set(sb, group, gdp, bitmap_bh); > > > - ext4_group_desc_csum_set(sb, group, gdp); > > > + bitmap_bh = ext4_read_block_bitmap(sb, group); > > > + if (IS_ERR(bitmap_bh)) { > > > + err = PTR_ERR(bitmap_bh); > > > + bitmap_bh = NULL; > > > + break; > > > + } > > > > > > - ext4_unlock_group(sb, group); > > > + err = -EIO; > > > + gdp = ext4_get_group_desc(sb, group, &gdp_bh); > > > + if (!gdp) > > > + break; > > > > > > - if (sbi->s_log_groups_per_flex) { > > > - ext4_group_t flex_group = ext4_flex_group(sbi, group); > > > - struct flex_groups *fg = sbi_array_rcu_deref(sbi, > > > - s_flex_groups, flex_group); > > > + ext4_lock_group(sb, group); > > > + already = 0; > > > + for (i = 0; i < clen; i++) > > > + if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == > > > + !state) > > > + already++; > > > > > > + clen_changed = clen - already; > > > if (state) > > > - atomic64_sub(clen_changed, &fg->free_clusters); > > > + ext4_set_bits(bitmap_bh->b_data, blkoff, clen); > > > else > > > - atomic64_add(clen_changed, &fg->free_clusters); > > > + mb_test_and_clear_bits(bitmap_bh->b_data, blkoff, clen); > > > + if (ext4_has_group_desc_csum(sb) && > > > + (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { > > > + gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT); > > > + ext4_free_group_clusters_set(sb, gdp, > > > + ext4_free_clusters_after_init(sb, group, gdp)); > > > + } > > > + if (state) > > > + clen = ext4_free_group_clusters(sb, gdp) - clen_changed; > > > + else > > > + clen = ext4_free_group_clusters(sb, gdp) + clen_changed; > > > + > > > + ext4_free_group_clusters_set(sb, gdp, clen); > > > + ext4_block_bitmap_csum_set(sb, group, gdp, bitmap_bh); > > > + ext4_group_desc_csum_set(sb, group, gdp); > > > + > > > + ext4_unlock_group(sb, group); > > > + > > > + if (sbi->s_log_groups_per_flex) { > > > + ext4_group_t flex_group = ext4_flex_group(sbi, group); > > > + struct flex_groups *fg = sbi_array_rcu_deref(sbi, > > > + s_flex_groups, flex_group); > > > + > > > + if (state) > > > + atomic64_sub(clen_changed, &fg->free_clusters); > > > + else > > > + atomic64_add(clen_changed, &fg->free_clusters); > > > + > > > + } > > > + > > > + err = ext4_handle_dirty_metadata(NULL, NULL, bitmap_bh); > > > + if (err) > > > + break; > > > + sync_dirty_buffer(bitmap_bh); > > > + err = ext4_handle_dirty_metadata(NULL, NULL, gdp_bh); > > > + sync_dirty_buffer(gdp_bh); > > > + if (err) > > > + break; > > > + > > > + block += thisgrp_len; > > > + len = len - thisgrp_len; > > ^^^ Maybe: len -= thisgrp_len; > > > > > + put_bh(bitmap_bh); > > ^^ brelse() would be more usual here... > > Sure, will make above two changes. > > Btw, any general rules of when should we use put_bh() v/s brelse()? > > Assumption about why I used put_bh() above was that in a non-error loop, > where we are doing ext4_read_block_bitmap() (which will return bh with > b_count elevated), I thought, we could simply do put_bh() in the end. > > But when there is a possibility of an error occurred somewhere in > between, then it's safe to do brelse(). The difference between put_bh() and brelse() are just the safety checks in brelse(). So I generally use brelse() in higher level code and put_bh() in lowlevel code where the overhead of additional checks could matter. But I guess the opinions can differ :). Honza
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 2f117ce3bb73..d0bd51b1e1ad 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -3901,72 +3901,93 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block, ext4_grpblk_t blkoff; int i, err; int already; - unsigned int clen, clen_changed; + unsigned int clen, clen_changed, thisgrp_len; - clen = EXT4_NUM_B2C(sbi, len); - - ext4_get_group_no_and_offset(sb, block, &group, &blkoff); - bitmap_bh = ext4_read_block_bitmap(sb, group); - if (IS_ERR(bitmap_bh)) { - err = PTR_ERR(bitmap_bh); - bitmap_bh = NULL; - goto out_err; - } - - err = -EIO; - gdp = ext4_get_group_desc(sb, group, &gdp_bh); - if (!gdp) - goto out_err; + while (len > 0) { + ext4_get_group_no_and_offset(sb, block, &group, &blkoff); - ext4_lock_group(sb, group); - already = 0; - for (i = 0; i < clen; i++) - if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) - already++; - - clen_changed = clen - already; - if (state) - ext4_set_bits(bitmap_bh->b_data, blkoff, clen); - else - mb_test_and_clear_bits(bitmap_bh->b_data, blkoff, clen); - if (ext4_has_group_desc_csum(sb) && - (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { - gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT); - ext4_free_group_clusters_set(sb, gdp, - ext4_free_clusters_after_init(sb, - group, gdp)); - } - if (state) - clen = ext4_free_group_clusters(sb, gdp) - clen_changed; - else - clen = ext4_free_group_clusters(sb, gdp) + clen_changed; + /* + * Check to see if we are freeing blocks across a group + * boundary. + * In case of flex_bg, this can happen that (block, len) may + * span across more than one group. In that case we need to + * get the corresponding group metadata to work with. + * For this we have goto again loop. + */ + thisgrp_len = min_t(unsigned int, (unsigned int)len, + EXT4_BLOCKS_PER_GROUP(sb) - EXT4_C2B(sbi, blkoff)); + clen = EXT4_NUM_B2C(sbi, thisgrp_len); - ext4_free_group_clusters_set(sb, gdp, clen); - ext4_block_bitmap_csum_set(sb, group, gdp, bitmap_bh); - ext4_group_desc_csum_set(sb, group, gdp); + bitmap_bh = ext4_read_block_bitmap(sb, group); + if (IS_ERR(bitmap_bh)) { + err = PTR_ERR(bitmap_bh); + bitmap_bh = NULL; + break; + } - ext4_unlock_group(sb, group); + err = -EIO; + gdp = ext4_get_group_desc(sb, group, &gdp_bh); + if (!gdp) + break; - if (sbi->s_log_groups_per_flex) { - ext4_group_t flex_group = ext4_flex_group(sbi, group); - struct flex_groups *fg = sbi_array_rcu_deref(sbi, - s_flex_groups, flex_group); + ext4_lock_group(sb, group); + already = 0; + for (i = 0; i < clen; i++) + if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == + !state) + already++; + clen_changed = clen - already; if (state) - atomic64_sub(clen_changed, &fg->free_clusters); + ext4_set_bits(bitmap_bh->b_data, blkoff, clen); else - atomic64_add(clen_changed, &fg->free_clusters); + mb_test_and_clear_bits(bitmap_bh->b_data, blkoff, clen); + if (ext4_has_group_desc_csum(sb) && + (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { + gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT); + ext4_free_group_clusters_set(sb, gdp, + ext4_free_clusters_after_init(sb, group, gdp)); + } + if (state) + clen = ext4_free_group_clusters(sb, gdp) - clen_changed; + else + clen = ext4_free_group_clusters(sb, gdp) + clen_changed; + + ext4_free_group_clusters_set(sb, gdp, clen); + ext4_block_bitmap_csum_set(sb, group, gdp, bitmap_bh); + ext4_group_desc_csum_set(sb, group, gdp); + + ext4_unlock_group(sb, group); + + if (sbi->s_log_groups_per_flex) { + ext4_group_t flex_group = ext4_flex_group(sbi, group); + struct flex_groups *fg = sbi_array_rcu_deref(sbi, + s_flex_groups, flex_group); + + if (state) + atomic64_sub(clen_changed, &fg->free_clusters); + else + atomic64_add(clen_changed, &fg->free_clusters); + + } + + err = ext4_handle_dirty_metadata(NULL, NULL, bitmap_bh); + if (err) + break; + sync_dirty_buffer(bitmap_bh); + err = ext4_handle_dirty_metadata(NULL, NULL, gdp_bh); + sync_dirty_buffer(gdp_bh); + if (err) + break; + + block += thisgrp_len; + len = len - thisgrp_len; + put_bh(bitmap_bh); + BUG_ON(len < 0); } - err = ext4_handle_dirty_metadata(NULL, NULL, bitmap_bh); if (err) - goto out_err; - sync_dirty_buffer(bitmap_bh); - err = ext4_handle_dirty_metadata(NULL, NULL, gdp_bh); - sync_dirty_buffer(gdp_bh); - -out_err: - brelse(bitmap_bh); + brelse(bitmap_bh); } /*
In case of flex_bg feature (which is by default enabled), extents for any given inode might span across blocks from two different block group. ext4_mb_mark_bb() only reads the buffer_head of block bitmap once for the starting block group, but it fails to read it again when the extent length boundary overflows to another block group. Then in this below loop it accesses memory beyond the block group bitmap buffer_head and results into a data abort. for (i = 0; i < clen; i++) if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) already++; This patch adds this functionality for checking block group boundary in ext4_mb_mark_bb() and update the buffer_head(bitmap_bh) for every different block group. w/o this patch, I was easily able to hit a data access abort using Power platform. <...> [ 74.327662] EXT4-fs error (device loop3): ext4_mb_generate_buddy:1141: group 11, block bitmap and bg descriptor inconsistent: 21248 vs 23294 free clusters [ 74.533214] EXT4-fs (loop3): shut down requested (2) [ 74.536705] Aborting journal on device loop3-8. [ 74.702705] BUG: Unable to handle kernel data access on read at 0xc00000005e980000 [ 74.703727] Faulting instruction address: 0xc0000000007bffb8 cpu 0xd: Vector: 300 (Data Access) at [c000000015db7060] pc: c0000000007bffb8: ext4_mb_mark_bb+0x198/0x5a0 lr: c0000000007bfeec: ext4_mb_mark_bb+0xcc/0x5a0 sp: c000000015db7300 msr: 800000000280b033 dar: c00000005e980000 dsisr: 40000000 current = 0xc000000027af6880 paca = 0xc00000003ffd5200 irqmask: 0x03 irq_happened: 0x01 pid = 5167, comm = mount <...> enter ? for help [c000000015db7380] c000000000782708 ext4_ext_clear_bb+0x378/0x410 [c000000015db7400] c000000000813f14 ext4_fc_replay+0x1794/0x2000 [c000000015db7580] c000000000833f7c do_one_pass+0xe9c/0x12a0 [c000000015db7710] c000000000834504 jbd2_journal_recover+0x184/0x2d0 [c000000015db77c0] c000000000841398 jbd2_journal_load+0x188/0x4a0 [c000000015db7880] c000000000804de8 ext4_fill_super+0x2638/0x3e10 [c000000015db7a40] c0000000005f8404 get_tree_bdev+0x2b4/0x350 [c000000015db7ae0] c0000000007ef058 ext4_get_tree+0x28/0x40 [c000000015db7b00] c0000000005f6344 vfs_get_tree+0x44/0x100 [c000000015db7b70] c00000000063c408 path_mount+0xdd8/0xe70 [c000000015db7c40] c00000000063c8f0 sys_mount+0x450/0x550 [c000000015db7d50] c000000000035770 system_call_exception+0x4a0/0x4e0 [c000000015db7e10] c00000000000c74c system_call_common+0xec/0x250 Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com> --- fs/ext4/mballoc.c | 131 +++++++++++++++++++++++++++------------------- 1 file changed, 76 insertions(+), 55 deletions(-)