From 42ac1848eac58875ceb081c2ed915d6f07ec1f30 Mon Sep 17 00:00:00 2001 From: Lukas Czerner Date: Mon, 8 Jun 2015 11:40:40 -0400 Subject: [PATCH] ext4: return error code from ext4_mb_good_group() Currently ext4_mb_good_group() only returns 0 or 1 depending on whether the allocation group is suitable for use or not. However we might get various errors and fail while initializing new group including -EIO which would never get propagated up the call chain. This might lead to an endless loop at writeback when we're trying to find a good group to allocate from and we fail to initialize new group (read error for example). Fix this by returning proper error code from ext4_mb_good_group() and using it in ext4_mb_regular_allocator(). In ext4_mb_regular_allocator() we will always return only the first occurred error from ext4_mb_good_group() and we only propagate it back to the caller if we do not get any other errors and we fail to allocate any blocks. Note that with other modes than errors=continue, we will fail immediately in ext4_mb_good_group() in case of error, however with errors=continue we should try to continue using the file system, that's why we're not going to fail immediately when we see an error from ext4_mb_good_group(), but rather when we fail to find a suitable block group to allocate from due to an problem in group initialization. Signed-off-by: Lukas Czerner Signed-off-by: Theodore Ts'o Reviewed-by: Darrick J. Wong --- fs/ext4/mballoc.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index df02951df6bf..78e58f7caafe 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2011,7 +2011,12 @@ void ext4_mb_scan_aligned(struct ext4_allocation_context *ac, } } -/* This is now called BEFORE we load the buddy bitmap. */ +/* + * This is now called BEFORE we load the buddy bitmap. + * Returns either 1 or 0 indicating that the group is either suitable + * for the allocation or not. In addition it can also return negative + * error code when something goes wrong. + */ static int ext4_mb_good_group(struct ext4_allocation_context *ac, ext4_group_t group, int cr) { @@ -2034,7 +2039,7 @@ static int ext4_mb_good_group(struct ext4_allocation_context *ac, if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) { int ret = ext4_mb_init_group(ac->ac_sb, group); if (ret) - return 0; + return ret; } fragments = grp->bb_fragments; @@ -2081,7 +2086,7 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac) { ext4_group_t ngroups, group, i; int cr; - int err = 0; + int err = 0, first_err = 0; struct ext4_sb_info *sbi; struct super_block *sb; struct ext4_buddy e4b; @@ -2148,6 +2153,7 @@ repeat: group = ac->ac_g_ex.fe_group; for (i = 0; i < ngroups; group++, i++) { + int ret = 0; cond_resched(); /* * Artificially restricted ngroups for non-extent @@ -2157,8 +2163,12 @@ repeat: group = 0; /* This now checks without needing the buddy page */ - if (!ext4_mb_good_group(ac, group, cr)) + ret = ext4_mb_good_group(ac, group, cr); + if (ret <= 0) { + if (!first_err) + first_err = ret; continue; + } err = ext4_mb_load_buddy(sb, group, &e4b); if (err) @@ -2170,9 +2180,12 @@ repeat: * We need to check again after locking the * block group */ - if (!ext4_mb_good_group(ac, group, cr)) { + ret = ext4_mb_good_group(ac, group, cr); + if (ret <= 0) { ext4_unlock_group(sb, group); ext4_mb_unload_buddy(&e4b); + if (!first_err) + first_err = ret; continue; } @@ -2219,6 +2232,8 @@ repeat: } } out: + if (!err && ac->ac_status != AC_STATUS_FOUND && first_err) + err = first_err; return err; } -- 2.39.5