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Message-ID: <20250508175908.1004880-3-harshadshirwadkar@gmail.com> Date: Thu, 8 May 2025 17:59:01 +0000 From: Harshad Shirwadkar <harshadshirwadkar@...il.com> To: linux-ext4@...r.kernel.org Cc: tytso@....edu, jack@...e.cz, harshads@...gle.com, Harshad Shirwadkar <harshadshirwadkar@...il.com> Subject: [PATCH v9 2/9] ext4: for committing inode, make ext4_fc_track_inode wait 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@...il.com> --- fs/ext4/fast_commit.c | 35 +++++++++++++++++++++++++++++++++++ fs/ext4/inline.c | 1 + fs/ext4/inode.c | 5 +++++ 3 files changed, 41 insertions(+) diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c index 63859ec6d..c4d3c71d5 100644 --- a/fs/ext4/fast_commit.c +++ b/fs/ext4/fast_commit.c @@ -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); } diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index 2c9b76292..fbc1c84b5 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -601,6 +601,7 @@ static int ext4_convert_inline_data_to_extent(struct address_space *mapping, goto out; } + ext4_fc_track_inode(handle, inode); ret = ext4_destroy_inline_data_nolock(handle, inode); if (ret) goto out; diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 94c7d2d82..d58b99407 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -696,6 +696,8 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode, if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN)) return retval; + + ext4_fc_track_inode(handle, inode); /* * New blocks allocate and/or writing to unwritten extent * will possibly result in updating i_data, so we take @@ -4072,6 +4074,7 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length) if (end_lblk > start_lblk) { ext4_lblk_t hole_len = end_lblk - start_lblk; + ext4_fc_track_inode(handle, inode); down_write(&EXT4_I(inode)->i_data_sem); ext4_discard_preallocations(inode); @@ -4224,6 +4227,7 @@ int ext4_truncate(struct inode *inode) if (err) goto out_stop; + ext4_fc_track_inode(handle, inode); down_write(&EXT4_I(inode)->i_data_sem); ext4_discard_preallocations(inode); @@ -5895,6 +5899,7 @@ ext4_reserve_inode_write(handle_t *handle, struct inode *inode, brelse(iloc->bh); iloc->bh = NULL; } + ext4_fc_track_inode(handle, inode); } ext4_std_error(inode->i_sb, err); return err; -- 2.49.0.1045.g170613ef41-goog
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